nanshe/nanshe/expanded_numpy.py: In the function roll, simplify the method for determining the start and end of the slicing.
nanshe/nanshe/expanded_numpy.py: In the function roll, simplify the method for determining the start and end of the slicing.

DudLab/nanshe,nanshe-org/nanshe,jakirkham/nanshe,nanshe-org/nanshe,DudLab/nanshe,jakirkham/nanshe