Nat.sub: def of Base
Import: import Base
Lines 683-690 of Base/base.bend: https://jend.leeeet.dev/read.txt?path=Base/base.bend&start_line=683&end_line=690

import Base

def Nat.sub(a: Nat, b: Nat) -> Nat:
  match a b:
    case 0n _:
      0n
    case 1n+ap 0n:
      1n+ap
    case 1n+ap 1n+bp:
      Nat.sub(ap, bp)

Uses (1):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat