    def forward(self, x):
        """
        x: (B, T, C)
        if num_groups=1: Normalisation on all T and C together for each B
        """
        x = x.transpose(1, 2)
        return super().forward(x).transpose(1, 2)
x: (B, T, C)
if num_groups=1: Normalisation on all T and C together for each B
demucs/transformer.py