null
```
Starting on goal: [think [user says [x y is a tennis player]]] and [say $x]
Goal arity 3: [think [user says [x y is a tennis player]]] and [say $x]
nextSolution
Got clause: _1 and _2
  Clause unifies to: [think [user says [x y is a tennis player]]] and [say $x]
  gdash: think [user says [x y is a tennis player]]
Goal arity 2: think [user says [x y is a tennis player]]
 Got clause: think _7
   Clause unifies to: think [user says [x y is a tennis player]]
  Clause is native.
   gdash: say $x
 Goal arity 2: say $x
  Got clause: say [ah , so _20 _21 must be a fit guy !]
    Clause unifies to: say [ah , so _20 _21 must be a fit guy !]
    gdash: user says [_20 _21 is a tennis player]
  Goal arity 3: user says [_20 _21 is a tennis player]
   Got clause: user says [x y is a tennis player]
     Clause unifies to: user says [x y is a tennis player]
     gdash: memorize [x y is supposedly a tennis player]
   Goal arity 2: memorize [x y is supposedly a tennis player]
    Got clause: memorize _50
      Clause unifies to: memorize [x y is supposedly a tennis player]
      gdash: [x y is supposedly a tennis player] or [memorized [x y is supposedly a tennis player]] or [memorize_impl [x y is supposedly a tennis player]]
    Goal arity 5: [x y is supposedly a tennis player] or [memorized [x y is supposedly a tennis player]] or [memorize_impl [x y is supposedly a tennis player]]
     Got clause: _69 or _70 or _71
       Clause unifies to: [x y is supposedly a tennis player] or [memorized [x y is supposedly a tennis player]] or [memorize_impl [x y is supposedly a tennis player]]
       gdash: x y is supposedly a tennis player
     Goal arity 7: x y is supposedly a tennis player
     Got clause: _76 or _77 or _78
       Clause unifies to: [x y is supposedly a tennis player] or [memorized [x y is supposedly a tennis player]] or [memorize_impl [x y is supposedly a tennis player]]
       gdash: memorized [x y is supposedly a tennis player]
     Goal arity 2: memorized [x y is supposedly a tennis player]
     Got clause: _99 or _100 or _101
       Clause unifies to: [x y is supposedly a tennis player] or [memorized [x y is supposedly a tennis player]] or [memorize_impl [x y is supposedly a tennis player]]
       gdash: memorize_impl [x y is supposedly a tennis player]
     Goal arity 2: memorize_impl [x y is supposedly a tennis player]
      Got clause: memorize_impl _107
        Clause unifies to: memorize_impl [x y is supposedly a tennis player]
       Clause is native.
Exception in native: java.lang.RuntimeException: Method 'incrementTheory' (static) with 1 parameter(s) not found in main
      Native clause fails
  Got clause: say [it's _132 !]
    Clause unifies to: say [it's _132 !]
    gdash: user says [_133 * _134]
  Goal arity 3: user says [_133 * _134]
  Got clause: say [_156 is tasty !]
    Clause unifies to: say [_156 is tasty !]
    gdash: user says [what is tasty]
  Goal arity 3: user says [what is tasty]

No solution```