Chacha20.at: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/src/crypto/chacha/chacha20.bend as Chacha20
Lines 35-39 of bend-collections@1.0.0.0/src/crypto/chacha/chacha20.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/src/crypto/chacha/chacha20.bend&start_line=35&end_line=39

import Base

def at(xs: List<&2, U32>, i: Nat) -> U32:
  match xs i:
    case Nil{} _: 0
    case x <> rest 0n: x
    case x <> rest 1n+p: at(rest, p)

Uses (3):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32