function compareTables(t1, t2)

  if type(t1) ~= 'table' or type(t2) ~= 'table' then

    return t1 == t2

  end

  -- compare common elements, check for extra elements in t1

  for k, v in pairs(t1) do

    local v2 = t2[k]

    if not compareTables(v, v2) then return false end

  end

  -- check for extra elements in t2

  for k, v in pairs(t2) do

    local v1 = t1[k]

    if v1 == nil then return false end

  end

  -- all matched, tables are equal

  return true

end