import java.math.*;
import javax.imageio.*;
import java.awt.image.*;
import java.awt.event.*;
import java.awt.*;
import java.security.spec.*;
import java.security.*;
import java.lang.management.*;
import java.lang.ref.*;
import java.lang.reflect.*;
import java.net.*;
import java.io.*;
import javax.swing.table.*;
import javax.swing.text.*;
import javax.swing.event.*;
import javax.swing.*;
import java.util.concurrent.atomic.*;
import java.util.concurrent.*;
import java.util.regex.*;
import java.util.List;
import java.util.zip.*;
import java.util.*;
public class main {

static int maxQuestionLength = 500;
static int maxAnswerLength = 200;

static String html(String subUri, Map<String, String> params) {
  List history = (List) ( get(getMainBot(), "history"));
  StringBuffer buf = new StringBuffer();
  
  buf.append(pageNav(params, litstringlist(), l(history), "n"));
  
  try { 
    int x = 0;
    print("l(history)=" + l(history) + ", x=" + x);
    
    int n;
    if (!empty(params.get("n")))
      n = parseInt(params.get("n"));
    else
      n = max(0, l(history)-1)/100*100;
    for (int i = min(n+100, l(history))-1; i >= n; i--) {
      Object dialog = history.get(i);
      String q = shorten(getString(dialog, "question"), maxQuestionLength);
      String a = shorten(getString(dialog, "answer"), maxAnswerLength);
      String user = or(getString(dialog, "user"), "User");
      buf.append(htag("li", htmlencode(user) + ": <b>" + htmlencode(q) + "</b>", "class", "splash-li") + "\n");
      buf.append(htag("li", system() + ": <b>" + htmlencode(a) + "</b>", "class", "splash-li") + "\n");
    }
  } catch (Throwable __e) { printStackTrace(__e); }
  return htag("p", "n=" + l(history)) + htag("ul", buf);
}

static <A> A or(A a, A b) {
  return a != null ? a : b;
}

static String htag(String tag, String contents, Object... params) {
  StringBuilder buf = new StringBuilder();
  buf.append("<" + tag);
  for (int i = 0; i < l(params); i += 2) {
    Object val = get(params, i+1);
    if (val != null) {
      String s = str(val);
      if (!empty(s))
        buf.append(" " + get(params, i) + "=" + htmlQuote(s));
    }
  }
  buf.append(">" + contents + "</" + tag + ">");
  return str(buf);
}

// the usual convenience shortcut for StringBuilder instead of string...
static String htag(String tag, StringBuilder contents, Object... params) {
  return htag(tag, str(contents), params);
}

// same with StringBuffer
static String htag(String tag, StringBuffer contents, Object... params) {
  return htag(tag, str(contents), params);
}

static int max(int a, int b) {
  return Math.max(a, b);
}

static long max(int a, long b) {
  return Math.max((long) a, b);
}

static int max(Collection<Integer> c) {
  int x = Integer.MIN_VALUE;
  for (int i : c) x = max(x, i);
  return x;
}

static double max(double[] c) {
  if (c.length == 0) return Double.MIN_VALUE;
  double x = c[0];
  for (int i = 1; i < c.length; i++) x = Math.max(x, c[i]);
  return x;
}


static List<String> litstringlist(String... data) {
  return litlist(data);
}

static String getString(Map map, Object key) {
  return map == null ? null : (String) map.get(key);
}

static String getString(List l, int idx) {
  return (String) get(l, idx);
}

static String getString(Object o, Object key) {
  if (o instanceof Map) return getString((Map) o, key);
  if (key instanceof String)
    return (String) get(o, (String) key);
  throw fail("Not a string key: " + getClassName(key));
}

static int l(Object[] array) {
  return array == null ? 0 : array.length;
}

static int l(byte[] array) {
  return array == null ? 0 : array.length;
}

static int l(int[] array) {
  return array == null ? 0 : array.length;
}

static int l(char[] array) {
  return array == null ? 0 : array.length;
}

static int l(Collection c) {
  return c == null ? 0 : c.size();
}

static int l(Map m) {
  return m == null ? 0 : m.size();
}

static int l(String s) {
  return s == null ? 0 : s.length();
} 



static Object mainBot;

static Object getMainBot() {
  return mainBot;
}

// 100 items per page
static String pageNav(Map<String, String> params, List<String> keepFields, int count, String nVar) {
  List<String> l = new ArrayList<String>();
  for (int i = 0; i < count; i += 100)
    l.add(tag("a", str(i/100+1), "href", selfLink(params, keepFields, nVar, str(i))));
  return tag("p", "Pages: " + join("\n", l));
}

  // automagically encode a whole map (keys+values)
  static Map htmlencode(Map o) {
    HashMap bla = new HashMap();
    for (Object key : keys(o)) {
      Object value = o.get(key);
      bla.put(htmlencode(key), htmlencode(value));
    }
    return bla;
  }

  static String htmlencode(Object o) {
    return htmlencode(string(o));
  }
  
  static String htmlencode(String s) {
    if (s == null) return "";
    StringBuilder out = new StringBuilder(Math.max(16, s.length()));
    for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (c > 127 || c == '"' || c == '<' || c == '>' || c == '&') {
            out.append("&#");
            out.append((int) c);
            out.append(';');
        } else {
            out.append(c);
        }
    }
    return out.toString();
  }

static boolean empty(Collection c) {
  return isEmpty(c);
}

static boolean empty(String s) {
  return isEmpty(s);
}

static boolean empty(Map map) {
  return map == null || map.isEmpty();
}

static int parseInt(String s) {
  return Integer.parseInt(s);
}

static StringBuffer print_log;

static void print() {
  print("");
}

static void print(Object o) {
  String s = String.valueOf(o) + "\n";
  synchronized(StringBuffer.class) {
    if (print_log == null) print_log = new StringBuffer();
  }
  print_log.append(s);
  System.out.print(s);
}

static void print(long l) {
  print(String.valueOf(l));
}

static int min(int a, int b) {
  return Math.min(a, b);
}

static double min(double[] c) {
  double x = Double.MAX_VALUE;
  for (double d : c) x = Math.min(x, d);
  return x;
}


static String shorten(String s, int max) {
  if (s == null) return "";
  return s.length() <= max ? s : s.substring(0, Math.min(s.length(), max)) + "...";
}

static String system() {
  return or((String) callOpt(getBot("#1002596"), "getName"), "System");
}

// get purpose 1: access a list/array (safer version of x.get(y))

static <A> A get(List<A> l, int idx) {
  return idx >= 0 && idx < l(l) ? l.get(idx) : null;
}

static <A> A get(A[] l, int idx) {
  return idx >= 0 && idx < l(l) ? l[idx] : null;
}

// get purpose 2: access a field by reflection

static Object get(Object o, String field) {
  if (o instanceof Class) return get((Class) o, field);
  
  if (o.getClass().getName().equals("main$DynamicObject"))
    return call(get_raw(o, "fieldValues"), "get", field);
    
  return get_raw(o, field);
}

static Object get_raw(Object o, String field) {
  try {
    Field f = get_findField(o.getClass(), field);
    f.setAccessible(true);
    return f.get(o);
  } catch (Exception e) {
    throw new RuntimeException(e);
  }
}

static Object get(Class c, String field) {
  try {
    Field f = get_findStaticField(c, field);
    f.setAccessible(true);
    return f.get(null);
  } catch (Exception e) {
    throw new RuntimeException(e);
  }
}

static Field get_findStaticField(Class<?> c, String field) {
  Class _c = c;
  do {
    for (Field f : _c.getDeclaredFields())
      if (f.getName().equals(field) && (f.getModifiers() & Modifier.STATIC) != 0)
        return f;
    _c = _c.getSuperclass();
  } while (_c != null);
  throw new RuntimeException("Static field '" + field + "' not found in " + c.getName());
}

static Field get_findField(Class<?> c, String field) {
  Class _c = c;
  do {
    for (Field f : _c.getDeclaredFields())
      if (f.getName().equals(field))
        return f;
    _c = _c.getSuperclass();
  } while (_c != null);
  throw new RuntimeException("Field '" + field + "' not found in " + c.getName());
}

static String string(Object o) {
  return String.valueOf(o);
}

static String htmlQuote(String s) {
  return "\"" + htmlencode(s) + "\"";
}

static <A, B> Set<A> keys(Map<A, B> map) {
  return map.keySet();
}

static Set keys(Object map) {
  return keys((Map) map);
}

  static Object callOpt(Object o, String method, Object... args) {
    try {
      if (o == null) return null;
      if (o instanceof Class) {
        Method m = callOpt_findStaticMethod((Class) o, method, args, false);
        if (m == null) return null;
        m.setAccessible(true);
        return m.invoke(null, args);
      } else {
        Method m = callOpt_findMethod(o, method, args, false);
        if (m == null) return null;
        m.setAccessible(true);
        return m.invoke(o, args);
      }
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }

  static Method callOpt_findStaticMethod(Class c, String method, Object[] args, boolean debug) {
    Class _c = c;
    while (c != null) {
      for (Method m : c.getDeclaredMethods()) {
        if (debug)
          System.out.println("Checking method " + m.getName() + " with " + m.getParameterTypes().length + " parameters");;
        if (!m.getName().equals(method)) {
          if (debug) System.out.println("Method name mismatch: " + method);
          continue;
        }

        if ((m.getModifiers() & Modifier.STATIC) == 0 || !callOpt_checkArgs(m, args, debug))
          continue;

        return m;
      }
      c = c.getSuperclass();
    }
    return null;
  }

  static Method callOpt_findMethod(Object o, String method, Object[] args, boolean debug) {
    Class c = o.getClass();
    while (c != null) {
      for (Method m : c.getDeclaredMethods()) {
        if (debug)
          System.out.println("Checking method " + m.getName() + " with " + m.getParameterTypes().length + " parameters");;
        if (m.getName().equals(method) && callOpt_checkArgs(m, args, debug))
          return m;
      }
      c = c.getSuperclass();
    }
    return null;
  }

  private static boolean callOpt_checkArgs(Method m, Object[] args, boolean debug) {
    Class<?>[] types = m.getParameterTypes();
    if (types.length != args.length) {
      if (debug)
        System.out.println("Bad parameter length: " + args.length + " vs " + types.length);
      return false;
    }
    for (int i = 0; i < types.length; i++)
      if (!(args[i] == null || isInstanceX(types[i], args[i]))) {
        if (debug)
          System.out.println("Bad parameter " + i + ": " + args[i] + " vs " + types[i]);
        return false;
      }
    return true;
  }



static <A> ArrayList<A> litlist(A... a) {
  return new ArrayList<A>(Arrays.asList(a));
}

static Object getBot(String botID) {
  return call(getMainBot(), "getBot", botID);
}


static String tag(String tag, String contents, Object... params) {
  return htag(tag, contents, params);
}

static String tag(String tag, StringBuilder contents, Object... params) {
  return htag(tag, contents, params);
}

static String tag(String tag, StringBuffer contents, Object... params) {
  return htag(tag, contents, params);
}

  public static String join(String glue, Iterable<String> strings) {
    StringBuilder buf = new StringBuilder();
    Iterator<String> i = strings.iterator();
    if (i.hasNext()) {
      buf.append(i.next());
      while (i.hasNext())
        buf.append(glue).append(i.next());
    }
    return buf.toString();
  }
  
  public static String join(String glue, String[] strings) {
    return join(glue, Arrays.asList(strings));
  }
  
  public static String join(Iterable<String> strings) {
    return join("", strings);
  }
  
  public static String join(String[] strings) {
    return join("", strings);
  }


static boolean isEmpty(Collection c) {
  return c == null || c.isEmpty();
}

static boolean isEmpty(String s) {
  return s == null || s.length() == 0;
}


static String selfLink(Map<String, String> params, List<String> keepFields, String... newValues) {
  Map<String, String> map = new TreeMap<String, String>();
  for (String key : keepFields) {
    String val = params.get(key);
    if (val != null)
      map.put(key, val);
  }
  for (int i = 0; i+1 < l(newValues); i += 2) {
    String key = get(newValues, i);
    String val = get(newValues, i+1);
    if (empty(key)) continue;
    if (empty(val))
      map.remove(key);
    else
      map.put(key, val);
  }
  return getActualURI() + htmlQuery(map);
}

static String str(Object o) {
  return String.valueOf(o);
}

  // varargs assignment fixer for a single string array argument
  static Object call(Object o, String method, String[] arg) {
    return call(o, method, new Object[] {arg});
  }
  
  static Object call(Object o, String method, Object... args) {
    try {
      if (o instanceof Class) {
        Method m = call_findStaticMethod((Class) o, method, args, false);
        m.setAccessible(true);
        return m.invoke(null, args);
      } else {
        Method m = call_findMethod(o, method, args, false);
        m.setAccessible(true);
        return m.invoke(o, args);
      }
    } catch (Exception e) {
      throw e instanceof RuntimeException ? (RuntimeException) e : new RuntimeException(e);
    }
  }

  static Method call_findStaticMethod(Class c, String method, Object[] args, boolean debug) {
    Class _c = c;
    while (c != null) {
      for (Method m : c.getDeclaredMethods()) {
        if (debug)
          System.out.println("Checking method " + m.getName() + " with " + m.getParameterTypes().length + " parameters");;
        if (!m.getName().equals(method)) {
          if (debug) System.out.println("Method name mismatch: " + method);
          continue;
        }

        if ((m.getModifiers() & Modifier.STATIC) == 0 || !call_checkArgs(m, args, debug))
          continue;

        return m;
      }
      c = c.getSuperclass();
    }
    throw new RuntimeException("Method '" + method + "' (static) with " + args.length + " parameter(s) not found in " + _c.getName());
  }

  static Method call_findMethod(Object o, String method, Object[] args, boolean debug) {
    Class c = o.getClass();
    while (c != null) {
      for (Method m : c.getDeclaredMethods()) {
        if (debug)
          System.out.println("Checking method " + m.getName() + " with " + m.getParameterTypes().length + " parameters");;
        if (m.getName().equals(method) && call_checkArgs(m, args, debug))
          return m;
      }
      c = c.getSuperclass();
    }
    throw new RuntimeException("Method '" + method + "' (non-static) with " + args.length + " parameter(s) not found in " + o.getClass().getName());
  }

  private static boolean call_checkArgs(Method m, Object[] args, boolean debug) {
    Class<?>[] types = m.getParameterTypes();
    if (types.length != args.length) {
      if (debug)
        System.out.println("Bad parameter length: " + args.length + " vs " + types.length);
      return false;
    }
    for (int i = 0; i < types.length; i++)
      if (!(args[i] == null || isInstanceX(types[i], args[i]))) {
        if (debug)
          System.out.println("Bad parameter " + i + ": " + args[i] + " vs " + types[i]);
        return false;
      }
    return true;
  }



  static RuntimeException fail() {
    throw new RuntimeException("fail");
  }
  
  static RuntimeException fail(Object msg) {
    throw new RuntimeException(String.valueOf(msg));
  }
  
  static RuntimeException fail(String msg) {
    throw new RuntimeException(unnull(msg));
  }
    
  static RuntimeException fail(String msg, Object... args) {
    throw new RuntimeException(format(msg, args));
  }

static String getClassName(Object o) {
  return o == null ? "null" : o.getClass().getName();
}


  static String unnull(String s) {
    return s == null ? "" : s;
  }
  
  static List unnull(List l) {
    return l == null ? emptyList() : l;
  }

static String htmlQuery(Map params) {
  return params.isEmpty() ? "" : "?" + makePostData(params);
}

static String htmlQuery(Object... data) {
  return htmlQuery(litmap(data));
}

// extended over Class.isInstance() to handle primitive types
static boolean isInstanceX(Class type, Object arg) {
  if (type == boolean.class) return arg instanceof Boolean;
  if (type == int.class) return arg instanceof Integer;
  if (type == long.class) return arg instanceof Long;
  if (type == float.class) return arg instanceof Float;
  if (type == short.class) return arg instanceof Short;
  if (type == char.class) return arg instanceof Character;
  if (type == byte.class) return arg instanceof Byte;
  if (type == double.class) return arg instanceof Double;
  return type.isInstance(arg);
}

  static String format(String pat, Object... args) {
    return format3(pat, args);
  }


static String getActualURI() {
  return (String) call(getMainBot(), "getActualURI");
}

  static String format3(String pat, Object... args) {
    if (args.length == 0) return pat;
    
    List<String> tok = javaTokPlusPeriod(pat);
    int argidx = 0;
    for (int i = 1; i < tok.size(); i += 2)
      if (tok.get(i).equals("*"))
        tok.set(i, format3_formatArg(argidx < args.length ? args[argidx++] : "null"));
    return join(tok);
  }
  
  static String format3_formatArg(Object arg) {
    if (arg == null) return "null";
    if (arg instanceof String) {
      String s = (String) arg;
      return isIdentifier(s) || isNonNegativeInteger(s) ? s : quote(s);
    }
    if (arg instanceof Integer || arg instanceof Long) return String.valueOf(arg);
    return quote(structure(arg));
  }
  


static List emptyList() {
  return Collections.emptyList();
}

static String makePostData(Map<Object, Object> map) {
  List<String> l = new ArrayList<String>();
  for (Map.Entry<Object, Object> e : map.entrySet()) {
    String key = (String) ( e.getKey());
    String value = structureOrText(e.getValue());
    l.add(urlencode(key) + "=" + urlencode(value));
  }
  return join("&", l);
}

static Map litmap(Object... x) {
  TreeMap map = new TreeMap();
  for (int i = 0; i < x.length-1; i += 2)
    if (x[i+1] != null)
      map.put(x[i], x[i+1]);
  return map;
}

static boolean isIdentifier(String s) {
  return isJavaIdentifier(s);
}

static String urlencode(String x) {
  try {
    return URLEncoder.encode(unnull(x), "UTF-8");
  } catch (UnsupportedEncodingException e) { throw new RuntimeException(e); }
}

  static String quote(String s) {
    if (s == null) return "null";
    return "\"" + s.replace("\\", "\\\\").replace("\"", "\\\"").replace("\r", "\\r").replace("\n", "\\n") + "\"";
  }
  
  static String quote(long l) {
    return quote("" + l);
  }


static boolean isNonNegativeInteger(String s) {
  return s != null && Pattern.matches("\\d+", s);
}

static String structure(Object o) {
  return structure(o, 0);
}

// leave to false, unless unstructure() breaks
static boolean structure_allowShortening = false;
  
static String structure(Object o, int stringSizeLimit) {
  if (o == null) return "null";
  String name = o.getClass().getName();
  
  StringBuilder buf = new StringBuilder();
  
  if (o instanceof Collection) { // TODO: store the type (e.g. HashSet/TreeSet)
    for (Object x : (Collection) o) {
      if (buf.length() != 0) buf.append(", ");
      buf.append(structure(x, stringSizeLimit));
    }
    return "[" + buf + "]";
  }
  
  if (o instanceof Map) {
    for (Object e : ((Map) o).entrySet()) {
      if (buf.length() != 0) buf.append(", ");
      buf.append(structure(((Map.Entry) e).getKey(), stringSizeLimit));
      buf.append("=");
      buf.append(structure(((Map.Entry) e).getValue(), stringSizeLimit));
    }
    return (o instanceof HashMap ? "hashmap" : "") + "{" + buf + "}";
  }
  
  if (o.getClass().isArray()) {
    int n = Array.getLength(o);
    for (int i = 0; i < n; i++) {
      if (buf.length() != 0) buf.append(", ");
      buf.append(structure(Array.get(o, i), stringSizeLimit));
    }
    return "array{" + buf + "}";
  }

  if (o instanceof String)
    return quote(stringSizeLimit != 0 ? shorten((String) o, stringSizeLimit) : (String) o);
    
  if (o instanceof Class)
    return "class(" + quote(((Class) o).getName()) + ")";
    
  if (o instanceof Throwable)
    return "exception(" + quote(((Throwable) o).getMessage()) + ")";
    
  if (o instanceof BigInteger)
    return "bigint(" + o + ")";
  
  if (o instanceof Double)
    return "d(" + quote(str(o)) + ")";
    
  if (o instanceof Long)
    return o + "L";
  
  // Need more cases? This should cover all library classes...
  if (name.startsWith("java.") || name.startsWith("javax."))
    return String.valueOf(o);
    
  String shortName = o.getClass().getName().replaceAll("^main\\$", "");
  
  int numFields = 0;
  String fieldName = "";
  if (shortName.equals("DynamicObject")) {
    shortName = (String) get(o, "className");
    Map<String, Object> fieldValues = (Map) get(o, "fieldValues");
    
    for (String _fieldName : fieldValues.keySet()) {
      fieldName = _fieldName;
      Object value = fieldValues.get(fieldName);
      if (value != null) {
        if (buf.length() != 0) buf.append(", ");
        buf.append(fieldName + "=" + structure(value, stringSizeLimit));
      }
      ++numFields;
   }
  } else {
    // regular class
    // TODO: go to superclasses too
    Field[] fields = o.getClass().getDeclaredFields();
    for (Field field : fields) {
      if ((field.getModifiers() & Modifier.STATIC) != 0)
        continue;
      Object value;
      try {
        field.setAccessible(true);
        value = field.get(o);
      } catch (Exception e) {
        value = "?";
      }
      
      fieldName = field.getName();
      
      // put special cases here...
  
      if (value != null) {
        if (buf.length() != 0) buf.append(", ");
        buf.append(fieldName + "=" + structure(value, stringSizeLimit));
      }
      ++numFields;
    }
  }
  
  String b = buf.toString();
  
  if (numFields == 1 && structure_allowShortening)
    b = b.replaceAll("^" + fieldName + "=", ""); // drop field name if only one
  String s = shortName;
  if (buf.length() != 0)
    s += "(" + b + ")";
  return s;
}

static String structureOrText(Object o) {
  return o instanceof String ? (String) o : structure(o);
}

// This is made for NL parsing.
// It's javaTok extended with "..." token, "$n" and "#n" and
// special quotes (which are converted to normal ones).

static List<String> javaTokPlusPeriod(String s) {
  List<String> tok = new ArrayList<String>();
  int l = s.length();
  
  int i = 0;
  while (i < l) {
    int j = i;
    char c; String cc;
    
    // scan for whitespace
    while (j < l) {
      c = s.charAt(j);
      cc = s.substring(j, Math.min(j+2, l));
      if (c == ' ' || c == '\t' || c == '\r' || c == '\n')
        ++j;
      else if (cc.equals("/*")) {
        do ++j; while (j < l && !s.substring(j, Math.min(j+2, l)).equals("*/"));
        j = Math.min(j+2, l);
      } else if (cc.equals("//")) {
        do ++j; while (j < l && "\r\n".indexOf(s.charAt(j)) < 0);
      } else
        break;
    }
    
    tok.add(s.substring(i, j));
    i = j;
    if (i >= l) break;
    c = s.charAt(i);
    cc = s.substring(i, Math.min(i+2, l));

    // scan for non-whitespace
    if (c == '\u201C' || c == '\u201D') c = '"'; // normalize quotes
    if (c == '\'' || c == '"') {
      char opener = c;
      ++j;
      while (j < l) {
        char _c = s.charAt(j);
        if (_c == '\u201C' || _c == '\u201D') _c = '"'; // normalize quotes
        if (_c == opener) {
          ++j;
          break;
        } else if (s.charAt(j) == '\\' && j+1 < l)
          j += 2;
        else
          ++j;
      }
      if (j-1 >= i+1) {
        tok.add(opener + s.substring(i+1, j-1) + opener);
        i = j;
        continue;
      }
    } else if (Character.isJavaIdentifierStart(c))
      do ++j; while (j < l && (Character.isJavaIdentifierPart(s.charAt(j)) || s.charAt(j) == '\'')); // for things like "this one's"
    else if (Character.isDigit(c))
      do ++j; while (j < l && Character.isDigit(s.charAt(j)));
    else if (cc.equals("[[")) {
      do ++j; while (j+1 < l && !s.substring(j, j+2).equals("]]"));
      j = Math.min(j+2, l);
    } else if (s.substring(j, Math.min(j+3, l)).equals("..."))
      j += 3;
    else if (c == '$' || c == '#')
      do ++j; while (j < l && Character.isDigit(s.charAt(j)));
    else
      ++j;

    tok.add(s.substring(i, j));
    i = j;
  }
  
  if ((tok.size() % 2) == 0) tok.add("");
  return tok;
}


static boolean isJavaIdentifier(String s) {
  if (s.length() == 0 || !Character.isJavaIdentifierStart(s.charAt(0)))
    return false;
  for (int i = 1; i < s.length(); i++)
    if (!Character.isJavaIdentifierPart(s.charAt(i)))
      return false;
  return true;
}

static void printStackTrace(Throwable e) {
  // we go to system.out now - system.err is nonsense
  print(getStackTrace(e));
}

static String getStackTrace(Throwable throwable) {
  StringWriter writer = new StringWriter();
  throwable.printStackTrace(new PrintWriter(writer));
  return writer.toString();
}
}