public function add( $key, $value ) {
		if ( ! array_key_exists( $key, $this->attributes ) ) {
			$this->attributes[ $key ] = $value;
		} else {
			if ( ! \is_array( $this->attributes[ $key ] ) ) {
				$this->attributes[ $key ] = array( $this->attributes[ $key ], $value );
			} else {
				$this->attributes[ $key ][] = $value;
			}
		}
	}
public function add( $key, $value ) {
		if ( ! array_key_exists( $key, $this->attributes ) ) {
			$this->attributes[ $key ] = $value;
		} else {
			if ( ! \is_array( $this->attributes[ $key ] ) ) {
				$this->attributes[ $key ] = array( $this->attributes[ $key ], $value );
			} else {
				$this->attributes[ $key ][] = $value;
			}
		}
	}
public function add ( $ key , $ value ) { if ( ! array_key_exists ( $ key , $ this -> attributes ) ) { $ this -> attributes [ $ key ] = $ value ; } else { if ( ! \ is_array ( $ this -> attributes [ $ key ] ) ) { $ this -> attributes [ $ key ] = array ( $ this -> attributes [ $ key ] , $ value ) ; } else { $ this -> attributes [ $ key ] [ ] = $ value ; } } }
Add to an new or existing value.
This will promote scalar values into an array to contain multiple values.

@param string $key
@param mixed  $value
Add to an new or existing value . This will promote scalar values into an array to contain multiple values .