'Retrieve a value from the given object.
If a callable is assembled on this object\'s attribute, and
passive is False, the callable will be executed and the
resulting value will be set as the new value for this attribute.'

def get(self, state, dict_, passive=PASSIVE_OFF):

    if (self.key in dict_):
        return dict_[self.key]
    else:
        key = self.key
        if ((key not in state.committed_state) or (state.committed_state[key] is NEVER_SET)):
            if (not (passive & CALLABLES_OK)):
                return PASSIVE_NO_RESULT
            if (key in state.callables):
                callable_ = state.callables[key]
                value = callable_(state, passive)
            elif self.callable_:
                value = self.callable_(state, passive)
            else:
                value = ATTR_EMPTY
            if ((value is PASSIVE_NO_RESULT) or (value is NEVER_SET)):
                return value
            elif (value is ATTR_WAS_SET):
                try:
                    return dict_[key]
                except KeyError:
                    raise KeyError(('Deferred    loader    for    attribute    %r    failed    to    populate    correctly' % key))
            elif (value is not ATTR_EMPTY):
                return self.set_committed_value(state, dict_, value)
        if (not (passive & INIT_OK)):
            return NEVER_SET
        else:
            return self.initialize(state, dict_)
