code: protected function validatorMethodName(MethodDefinition $methodDefinition)
      {
          $this->typeCheck->validatorMethodName(func_get_args());
  
          $methodName = $methodDefinition->name();
          if ('__' === substr($methodName, 0, 2)) {
              $methodName = sprintf(
                  'validate%s',
                  ucfirst(substr($methodName, 2))
              );
          }
  
          return $methodName;
      }
docs: @param MethodDefinition $methodDefinition
  
  @return string