call: ['mut'] ID ['(' parameters ')']

def call(self):
        """
        call: ['mut'] ID ['(' parameters ')']
        """
        is_mutable = False
        if self.token.nature == Nature.MUT:
            is_mutable = True
            self._process(Nature.MUT)

        identifier = Identifier(name=self.token.value)
        self._process(Nature.ID)

        if self.token.nature == Nature.LPAREN:
            return FunctionCall(identifier=identifier, parameters=self.parameters())
        else:
            return Variable(identifier=identifier, is_mutable=is_mutable)