function escapeRegExp(string) {
	      string = toString(string);
	      return (string && reHasRegExpChar.test(string))
	        ? string.replace(reRegExpChar, '\\$&')
	        : string;
	    }
Converts `string` to
[kebab case](https://en.wikipedia.org/wiki/Letter_case#Special_case_styles).

@static
@memberOf _
@since 3.0.0
@category String
@param {string} [string=''] The string to convert.
@returns {string} Returns the kebab cased string.
@example

_.kebabCase('Foo Bar');
// => 'foo-bar'

_.kebabCase('fooBar');
// => 'foo-bar'

_.kebabCase('__FOO_BAR__');
// => 'foo-bar'