Gets the first key from given value.

        :param value: Value.
        :type value: object
        :return: Key.
        :rtype: object

def get_first_key_from_value(self, value):
        """
        Gets the first key from given value.

        :param value: Value.
        :type value: object
        :return: Key.
        :rtype: object
        """

        for key, data in self.iteritems():
            if data == value:
                return key