function_body: '{' (statement)* '}'

def function_body(self):
        """
        function_body: '{' (statement)* '}'
        """
        root = FunctionBody()
        self._process(Nature.LBRACKET)

        while self.token.nature != Nature.RBRACKET:
            root.children.append(self.statement())

        self._process(Nature.RBRACKET)
        return root