This is the same as tensoring f with the identity map of N.
When N is a free module of rank 1 the net effect of the operation is to shift the degrees of f.
| i1 : R = ZZ/101[t] | 
| i2 : f = matrix {{t}} | 
| i3 : degrees source f | 
| i4 : degrees source (f ** R^{-3}) | 




