def inspect
      # result = "#{self.class}["
      result = "{"
      i = 0
      each do |key, val|
        result << ', ' if i > 0
        result << key.inspect << ' => ' << val.inspect
        i += 1
      end
      return result << "}"
    end
def inspect
      # result = "#{self.class}["
      result = "{"
      i = 0
      each do |key, val|
        result << ', ' if i > 0
        result << key.inspect << ' => ' << val.inspect
        i += 1
      end
      return result << "}"
    end
See `Object#hash`.
 @return [Integer]
 Return the contents of this `Map` as a programmer-readable `String`. If all the
 keys and values are serializable as Ruby literal strings, the returned string can
 be passed to `eval` to reconstitute an equivalent `Map`. The default
 block (if there is one) will be lost when doing this, however.

 @return [String]