class_docstr: Flatten layer
  This module is to replace the last fc layer of the pre-trained model with a flatten layer. It flattens the input
  tensor to a 2D vector, which is (B, N). B is the batch size and N is the product of all dimensions except
  the batch size.
  
  Examples:
      >>> x = torch.randn(8, 3, 224, 224)
      >>> x = Flatten()(x)
      >>> print(x.shape)
      >>> (8, 150528)
code: def __init__(self):
      super(Flatten, self).__init__()
  
imports: import torch.nn
  from torch.nn import functional
  from torchvision import models
label_desc: Use image node_id 1 to create a new Flatten object from inherited base classes: nn with example: obj = Flatten()