_ifTwoCodePointsAreValidEscape = (input, pos, f, s) => {
	// This section describes how to check if two code points are a valid escape.
	// The algorithm described here can be called explicitly with two code points, or can be called with the input stream itself.
	// In the latter case, the two code points in question are the current input code point and the next input code point, in that order.

	// Note: This algorithm will not consume any additional code point.
	const first = f || input.charCodeAt(pos - 1);
	const second = s || input.charCodeAt(pos);

	// If the first code point is not U+005C REVERSE SOLIDUS (\), return false.
	if (first !== CC_REVERSE_SOLIDUS) return false;
	// Otherwise, if the second code point is a newline, return false.
	if (_isNewline(second)) return false;
	// Otherwise, return true.
	return true;
}
@param {string} input input
@param {number} pos position
@param {number=} f first code point
@param {number=} s second code point
@returns {boolean} true if two code points are a valid escape