code: protected function addCall($method, $args)
      {
          if (! isset($this->call_counts[$method])) {
              $this->call_counts[$method] = 0;
          }
          $this->call_counts[$method]++;
      }
docs: Adds one to the call count of a method.
  
  @param string $method        Method called.
  @param array $args           Arguments as an array.