public function where($first, $operator, $second, $boolean = 'and')
    {
        return $this->on($first, $operator, $second, $boolean, true);
    }
public function where($first, $operator, $second, $boolean = 'and')
    {
        return $this->on($first, $operator, $second, $boolean, true);
    }
public function where ( $ first , $ operator , $ second , $ boolean = 'and' ) { return $ this -> on ( $ first , $ operator , $ second , $ boolean , true ) ; }
Add an "on where" clause to the join.

@param  string  $first
@param  string  $operator
@param  string  $second
@param  string  $boolean
@return \Nova\Database\Query\JoinClause
Add an on where clause to the join .