Fuse modules.
Return a list of modules that fuses the operations specified in the input module list.
Fuses only the following sequence of modules:
conv, bn;
conv, bn, relu;
conv, relu;
conv, bn, add;
conv, bn, add, relu;
conv, add;
conv, add, relu;
linear, bn;
linear, bn, relu;
linear, relu;
linear, bn, add;
linear, bn, add, relu;
linear, add;
linear, add, relu.
For these sequences, the first element in the output module list performs the fused operation. The rest of the elements are set to nn.Identity()