code: def validate(name, re=None, convert=None, doc=None):
      
  
      def wrap(cls_or_func):
          if not hasattr(cls_or_func, '_validations'):
              cls_or_func._validations = {}
          cls_or_func._validations[name] = {'re': re, 'convert': convert, 'doc': doc}
          return cls_or_func
      return wrap
docs: Decorator. Apply on a :class:`wsgiservice.Resource` or any of it's
      methods to validates a parameter on input. When a parameter does not
      validate, a :class:`wsgiservice.exceptions.ValidationException` exception
      will be thrown.
  
      :param name: Name of the input parameter to validate.
      :type name: string
      :param re: Regular expression to search for in the input parameter. If
                 this is not set, just validates if the parameter has been set.
      :type re: regular expression
      :param convert: Callable to convert the validated parameter value to the
                      final data type. Ideal candidates for this are the
                      built-ins int or float functions. If the function raises a
                      ValueError, this is reported to the client as a 400 error.
      :type convert: callable
      :param doc: Parameter description for the API documentation.
      :type doc: string