/**
 * @author Jonathan Barronville
 * @param  {String}  hex_string
 * @return {Boolean}
 */
function isHexColorString( hex_string ) {
    'use strict';

    if ( {}.toString.call( hex_string ) !== '[object String]' ) {
        return false;
    }

    hex_string = hex_string.trim();

    if ( ! ( /^[0-9a-f]{6}$/i ).test( hex_string ) ) {
        return false;
    }

    return true;
}