assertCopyArray = (arr, optNameOfArray = 'Alleged array') => {
  const passStyle = passStyleOf(arr);
  passStyle === 'copyArray' ||
    Fail`${q(optNameOfArray)} ${arr} must be a pass-by-copy array, not ${q(
      passStyle,
    )}`;
}
@param {any} arr
@param {string=} optNameOfArray
@returns {asserts arr is CopyArray<any>}