public function addGroup($group)
    {
        if (null === $this->groups) {
            $this->groups = [];
        }
        if (!in_array($group, $this->groups)) {
            $this->groups[] = $group;
        }

        return $this;
    }
public function addGroup($group)
    {
        if (null === $this->groups) {
            $this->groups = [];
        }
        if (!in_array($group, $this->groups)) {
            $this->groups[] = $group;
        }

        return $this;
    }
public function addGroup ( $ group ) { if ( null === $ this -> groups ) { $ this -> groups = [ ] ; } if ( ! in_array ( $ group , $ this -> groups ) ) { $ this -> groups [ ] = $ group ; } return $ this ; }
Adds a normalization group.

@param string $group

@return self
Adds a normalization group .