php import function from another file

1File1.php :
2<?php
3  function first($int, $string){ //function parameters, two variables.
4    return $string;  //returns the second argument passed into the function
5  }
6?>
7  
8File2.php :
9<?php
10  include 'File1.php';
11  echo first(1,"omg lol"); //returns omg lol;
12?>