class MaxPool2:
  # ...

  def forward(self, input):
    '''
    Performs a forward pass of the maxpool layer using the given input.
    Returns a 3d numpy array with dimensions (h / 2, w / 2, num_filters).
    - input is a 3d numpy array with dimensions (h, w, num_filters)
    '''
    self.last_input = input

    # More implementation
    # ...