GradedModuleMap || GradedModuleMap -- a binary operator, often used for vertical concatenation

i1 : f = gradedModuleMap( matrix "1;2", matrix "2,3" )

          2              1
o1 = 0: ZZ  <--| 1 |-- ZZ  :0
               | 2 |

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

o1 : GradedModuleMap

i2 : f||f

          4              1
o2 = 0: ZZ  <--| 1 |-- ZZ  :0
               | 2 |
               | 1 |
               | 2 |

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

o2 : GradedModuleMap