public String value(String... keys) {
        return get(keys).value();
    }
Returns the value for that key. <br>
It is a shortcut for: <br>
<br>
<code>
get("user").get("name").value()
get("user").value("name")
</code>

@param keys the key(s)
@return the value
src/main/java/spark/QueryParamsMap.java