API Version 2015-10-01 defines the following filters for DescribeDhcpOptions:

        * dhcp-options-id
        * key
        * value
        * tag:key=value
        * tag-key
        * tag-value

        Taken from: http://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeDhcpOptions.html

def get_filter_value(self, filter_name):
        """
        API Version 2015-10-01 defines the following filters for DescribeDhcpOptions:

        * dhcp-options-id
        * key
        * value
        * tag:key=value
        * tag-key
        * tag-value

        Taken from: http://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeDhcpOptions.html
        """
        if filter_name == 'dhcp-options-id':
            return self.id
        elif filter_name == 'key':
            return list(self._options.keys())
        elif filter_name == 'value':
            values = [item for item in list(self._options.values()) if item]
            return itertools.chain(*values)
        else:
            return super(DHCPOptionsSet, self).get_filter_value(
                filter_name, 'DescribeDhcpOptions')