gradedModuleMap -- make a map of graded modules

i1 : gradedModuleMap(random(ZZ^3,ZZ^4),random(ZZ^2,ZZ^2))

          3                    4
o1 = 0: ZZ  <--| 4 3 8 1 |-- ZZ  :0
               | 2 0 8 6 |
               | 5 4 9 1 |

          2                2
     1: ZZ  <--| 3 5 |-- ZZ  :1
               | 5 9 |

o1 : GradedModuleMap