function encodeBasic(codePoint, flag) {
		codePoint -= (codePoint - 97 < 26) << 5;
		return codePoint + (!flag && codePoint - 65 < 26) << 5;
	}
Converts a basic code point to lowercase is `flag` is falsy, or to
uppercase if `flag` is truthy. The code point is unchanged if it's
caseless. The behavior is undefined if `codePoint` is not a basic code
point.
@private
@param {Number} codePoint The numeric value of a basic code point.
@returns {Number} The resulting basic code point.