///|
test "core byte api probe" {
  let source = @utf8.encode("ok", bom=false)
  let buffer = @buffer.Buffer(size_hint=4)
  buffer.write_byte(source[0])
  let output = buffer.to_bytes()
  assert_eq(output.length(), 1)
  let fixed = FixedArray::make(4, Byte::default())
  assert_eq(fixed.length(), 4)
}