original_string: public function whereNull($fields)
      {
          if (!is_array($fields)) {
              $fields = [$fields];
          }
  
          $exp = $this->newExpr();
  
          foreach ($fields as $field) {
              $exp->isNull($field);
          }
  
          return $this->where($exp);
      }
code: public function whereNull($fields)
      {
          if (!is_array($fields)) {
              $fields = [$fields];
          }
  
          $exp = $this->newExpr();
  
          foreach ($fields as $field) {
              $exp->isNull($field);
          }
  
          return $this->where($exp);
      }
code_tokens: public function whereNull ( $ fields ) { if ( ! is_array ( $ fields ) ) { $ fields = [ $ fields ] ; } $ exp = $ this -> newExpr ( ) ; foreach ( $ fields as $ field ) { $ exp -> isNull ( $ field ) ; } return $ this -> where ( $ exp ) ; }
docstring: Convenience method that adds a IS NULL condition to the query
  
  @param array|string|\Cake\Database\ExpressionInterface $fields A single field or expressions or a list of them that should be null
  @return $this
docstring_tokens: Convenience method that adds a IS NULL condition to the query