class Scope(object):
    __shared_state = {}
    __current_function = None
    __functions = {}

    def __init__(self):
        self.__dict__ = self.__shared_state

    def new(self, name, symbols = []):
        if getattr(self.__functions, name, None):
            raise ScopeError("multiple definitions of %s" % name)
        self.__functions[name] = []
        self.__current_function = name
        self.add(symbols)

    def add(self, symbols):
        if type(symbols) != type([]):
            symbols = [symbols]
        for symbol in symbols:
            if symbol not in self.__functions[self.__current_function]:
                self.__functions[self.__current_function].append(symbol)

    def contains(self, name):
        return name in self.__functions[self.__current_function]

    def __str__(self):
        return "<Scope: %s>" % str(self.__functions)