(re)name operations in unfolded SFGs

I think it could be useful to rename the operations in an unfolded SFG, at least using an optional keyword argument.

For example if an operation has a name "foo", the resulting copies of that operation can be "foo_0", "foo_1" etc. I think it should be possible to simply loop through all operations in a "sub-SFG" and if a name is set, append an index if the argument is True. For delays, it may not be as simple...