Natural.inv_step: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/src/math/natural.bend as Natural
Lines 300-303 of bend-collections@1.0.0.0/src/math/natural.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/src/math/natural.bend&start_line=300&end_line=303

import Base

# Extended Euclid on (m, a mod m) keeping only the coefficient of a, mod m:
# a * s0 == r0 and a * s1 == r1 (mod m). The remainders are gcd's.
def inv_step(+m: Nat, +q: Nat, +s0: Nat, +s1: Nat) -> Nat:
  Nat.mod(Nat.add(s0, Nat.sub(m, Nat.mod(Nat.mul(q, s1), m))), m)

Uses (5):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.mod
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.mul
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.sub