func lchop*(s, sub: string): string =
  ## Remove ``sub`` from the beginning of ``s``.
  runnableExamples:
    let s = "ABcde"
    doAssert s.lchop("AB") == "cde"
    doAssert s.lchop("XXX") == "ABcde"

  if s.startsWith(sub):
    s[sub.len .. s.high]
  else:
    s

func rchop*(s, sub: string): string =
  ## Remove ``sub`` from the end of ``s``.
  runnableExamples:
    let fname = "stuff.nim"
    doAssert fname.rchop(".nim") == "stuff"
    doAssert fname.rchop(".jpg") == "stuff.nim"
    let longer = "nim is a great language"
    doAssert longer.rchop("uage") == "nim is a great lang"

  if s.endsWith(sub):
    s[0 ..< ^sub.len]
  else:
    s