# Codeblock 9
class Encoder(nn.Module):
   def __init__(self):
       super().__init__()
       self.patcher = Patcher()  #(1)
       self.learnable_embedding = LearnableEmbedding()  #(2)

       #(3)
       self.encoder_blocks = nn.ModuleList(EncoderBlock() for _ in range(NUM_ENCODER_BLOCKS))
  
   def forward(self, images):  #(4)
       print(f'images\t\t\t: {images.size()}')
      
       features = self.patcher(images)  #(5)
       print(f'after patcher\t\t: {features.size()}')
      
       features = features + self.learnable_embedding()  #(6)
       print(f'after learn embed\t: {features.size()}')
      
       for i, encoder_block in enumerate(self.encoder_blocks):
           features = encoder_block(features)  #(7)
           print(f"after encoder block #{i}\t: {features.shape}")

       return features