def get_available_voices(self, language=None, gender=None):
        """
        Returns a list of available voices, via 'ListVoices' endpoint

        Docs:
            http://developer.ivona.com/en/speechcloud/actions.html#ListVoices

        :param language: returned voices language
        :type language: str
        :param gender: returned voices gender
        :type gender: str
        """
        endpoint = 'ListVoices'

        data = dict()
        if language:
            data.update({'Voice': {'Language': language}})

        if gender:
            data.update({'Voice': {'Gender': gender}})

        print(data)

        response = self._get_response('get', endpoint, data)

        return response.json()['Voices']
Returns a list of available voices, via 'ListVoices' endpoint

        Docs:
            http://developer.ivona.com/en/speechcloud/actions.html#ListVoices

        :param language: returned voices language
        :type language: str
        :param gender: returned voices gender
        :type gender: str