function isClass( value ) {
	var str;
	if ( !isFunction( value ) ) {
		return false;
	}
	str = function2string( value );
	return RE_CLASS.test( str );
}
Tests if a value is a class.

@param {*} value - value to test
@returns {boolean} boolean indicating whether value is a class

@example
var bool = isClass( class Person {} );
// returns true

@example
var bool = isClass( function Person() {} );
// returns false

@example
var bool = isClass( null );
// returns false