gradedModuleMap -- make a map of graded modules

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

          3                    4
o1 = 0: ZZ  <--| 5 8 7 4 |-- ZZ  :0
               | 5 7 9 4 |
               | 3 5 5 0 |

          2                2
     1: ZZ  <--| 0 9 |-- ZZ  :1
               | 5 1 |

o1 : GradedModuleMap