Blake3.low_bytes: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend as Blake3
Lines 160-168 of bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend&start_line=160&end_line=168

import Base

# A block holding len bytes (len <= 64) is zero past them: the word at byte
# offset pos keeps its min(4, len - pos) low bytes.
def low_bytes(w: U32, k: Nat) -> U32:
  match k:
    case 0n: 0
    case 1n: U32.and(w,255)
    case 2n: U32.and(w,65535)
    case 3n: U32.and(w,16777215)
    case 4n+q: w

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