# Codeblock 2a
class SEModule(nn.Module):
    def __init__(self, num_channels, r):                     #(1)
        super().__init__()
        
        self.global_pooling = nn.AdaptiveAvgPool2d(output_size=(1,1))  #(2)
        self.fc0 = nn.Linear(in_features=num_channels,       #(3)
                             out_features=num_channels//r, 
                             bias=False)
        self.relu = nn.ReLU()                                #(4)
        self.fc1 = nn.Linear(in_features=num_channels//r,    #(5)
                             out_features=num_channels, 
                             bias=False)
        self.sigmoid = nn.Sigmoid()                          #(6)