Perm.internal_shift: def of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/perm.bend as Perm
Lines 6-11 of bend-mathlib@0.8.1.0/perm.bend: https://jend.leeeet.dev/read.txt?path=bend-mathlib@0.8.1.0/perm.bend&start_line=6&end_line=11

import Base

def internal_shift(+s: List<&2, Nat>) -> List<&2, Nat>:
  match s:
    case Nil{}:
      Nil{}
    case +i <> rest:
      (1n+i) <> internal_shift(rest)

Uses (2):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat