Fixed bug in computing shape of Flatten layer

    super(Flatten, self).__init__(**kwargs)

    try:

      parent_shape = self.in_layers[0].shape

      self._shape = parent_shape[:2]

      for s in parent_shape[2:]:

        self._shape[1] *= s

      s = list(parent_shape[:2])

      for x in parent_shape[2:]:

        s[1] *= x

      self._shape = tuple(s)

    except:

      pass