examples/research_projects/visual_bert/modeling_frcnn.py/BottleneckBlock/forward
class BottleneckBlock:    def forward(self, x):
        out = self.conv1(x)
        out = nn.functional.relu_(out)

        out = self.conv2(out)
        out = nn.functional.relu_(out)

        out = self.conv3(out)

        if self.shortcut is not None:
            shortcut = self.shortcut(x)
        else:
            shortcut = x

        out += shortcut
        out = nn.functional.relu_(out)
        return out