code: public function addItem(array $item): self
      {
          if (count($item) < 2) {
              throw new Exception('Invalid count of item elements.');
          }
          $this->items[] = $item;
          return $this;
      }
docs: The method adds a set of fields and their corresponding rules and parameters
  for validating the input data
  @param array $item This set is an array whose first element is a string
  with a field name (or an array of field names), the second element is the
  name of the validation rule (always a string), the third element is an
  optional array of validation options.
  @return self
  @throws \extensions\validator\Exception