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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_state(self, key=None, drop_defaults=False):
 """Gets the widget state, or a piece of it. Parameters key : unicode or iterable (optional) A single property's name or iterable of property names to get. Returns ------- state : dict of states metadata : dict metadata for each field: {key: metadata} """

        if key is None:
            keys = self.keys
        elif isinstance(key, string_types):
            keys = [key]
        elif isinstance(key, collections.Iterable):
            keys = key
        else:
            raise ValueError("key must be a string, an iterable of keys, or None")
        state = {}
        traits = self.traits()
        for k in keys:
            to_json = self.trait_metadata(k, 'to_json', self._trait_to_json)
            value = to_json(getattr(self, k), self)
            if not PY3 and isinstance(traits[k], Bytes) and isinstance(value, bytes):
                value = memoryview(value)
            if not drop_defaults or not self._compare(value, traits[k].default_value):
                state[k] = value
        return state