src/Config/Config.php
public function add($key, $value) {
        if (isset($this->data[$key])) {
            throw new \InvalidArgumentException("Key $key is already set");
        }
        $this->data[$key] = $value;
    }
public function add($key, $value) {
        if (isset($this->data[$key])) {
            throw new \InvalidArgumentException("Key $key is already set");
        }
        $this->data[$key] = $value;
    }
public function add ( $ key , $ value ) { if ( isset ( $ this -> data [ $ key ] ) ) { throw new \ InvalidArgumentException ( "Key $key is already set" ) ; } $ this -> data [ $ key ] = $ value ; }
Add a new key value pairing.

@throws InvalidArgumentException if the key is already set
Add a new key value pairing .