Validates that the response matches the return type for the function  

        Returns two element tuple: (bool, string)

        - `bool` - True if valid, False if not
        - `string` - Description of validation error, or None if valid

        :Parameters:
          iface_name
            Name of interface
          func_name
            Name of function
          resp
            Result from calling the function

def validate_response(self, iface_name, func_name, resp):
        """
        Validates that the response matches the return type for the function  

        Returns two element tuple: (bool, string)

        - `bool` - True if valid, False if not
        - `string` - Description of validation error, or None if valid

        :Parameters:
          iface_name
            Name of interface
          func_name
            Name of function
          resp
            Result from calling the function
        """
        self.interface(iface_name).function(func_name).validate_response(resp)