Online PHP editor | output for BvVp1

<?php function contextCheck( $context = false ) { # URL Paremeter Checker # If the infomation passed is a string and isn't empty, grab URL paremeter if( trim( $context ) !== false and is_string( $context )) { # Check if the URL Parameter even exists if ( isset( $_GET["{$context}"] ) ) { $URL_Parameter = $_GET["{$context}"]; # If the URL Parameter is a string and isn't empty, return true if( !empty( $URL_Parameter ) and is_string( $URL_Parameter ) ) { return $URL_Parameter; } } } else { return false; } } $_GET['foo'] = '12'; $_GET['bar'] = '0'; print( contextCheck( 'foo' ) ); print( contextCheck( 'bar' ) ); # This doesn't output :[ ?>