How to use the pulsectl._pulsectl.PA_CVOLUME function in pulsectl

('mute', c_int),
		('proplist', POINTER(PA_PROPLIST)),
		('corked', c_int),
		('has_volume', c_int),
		('volume_writable', c_int),
	]

class PA_SINK_INFO(Structure):
	_fields_ = [
		('name', c_char_p),
		('index', c_uint32),
		('description', c_char_p),
		('sample_spec', PA_SAMPLE_SPEC),
		('channel_map', PA_CHANNEL_MAP),
		('owner_module', c_uint32),
		('volume', PA_CVOLUME),
		('mute', c_int),
		('monitor_source', c_uint32),
		('monitor_source_name', c_char_p),
		('latency', PA_USEC_T),
		('driver', c_char_p),
		('flags', c_int),
		('proplist', POINTER(PA_PROPLIST)),
		('configured_latency', PA_USEC_T),
		('base_volume', c_int),
		('state', c_int),
		('n_volume_steps', c_int),
		('card', c_uint32),
		('n_ports', c_uint32),
		('ports', POINTER(POINTER(PA_PORT_INFO))),
		('active_port', POINTER(PA_PORT_INFO)),
	]

def to_struct(self):
		return c.PA_CVOLUME(
			len(self.values), tuple(min( c.PA_VOLUME_UI_MAX,
					int(round(v * c.PA_VOLUME_NORM)) ) for v in self.values) )

pa_context_move_source_output_by_index=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, c_uint32, PA_CONTEXT_SUCCESS_CB_T, c_void_p] ),
		pa_context_set_source_output_volume=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, POINTER(PA_CVOLUME), PA_CONTEXT_SUCCESS_CB_T, c_void_p] ),
		pa_context_set_source_output_mute=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, c_int, PA_CONTEXT_SUCCESS_CB_T, c_void_p] ),
		pa_context_kill_source_output=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, PA_CONTEXT_SUCCESS_CB_T, c_void_p] ),
		pa_context_get_source_info_list=( 'pa_op',
			[POINTER(PA_CONTEXT), PA_SOURCE_INFO_CB_T, c_void_p] ),
		pa_context_get_source_info_by_name=( 'pa_op',
			[POINTER(PA_CONTEXT), c_str_p, PA_SOURCE_INFO_CB_T, c_void_p] ),
		pa_context_get_source_info_by_index=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, PA_SOURCE_INFO_CB_T, c_void_p] ),
		pa_context_set_source_volume_by_index=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, POINTER(PA_CVOLUME), PA_CONTEXT_SUCCESS_CB_T, c_void_p] ),
		pa_context_set_source_mute_by_index=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, c_int, PA_CONTEXT_SUCCESS_CB_T, c_void_p] ),
		pa_context_suspend_source_by_index=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, c_int, PA_CONTEXT_SUCCESS_CB_T, c_void_p] ),
		pa_context_set_source_port_by_index=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, c_str_p, PA_CONTEXT_SUCCESS_CB_T, c_void_p] ),
		pa_context_get_client_info_list=( 'pa_op',
			[POINTER(PA_CONTEXT), PA_CLIENT_INFO_CB_T, c_void_p] ),
		pa_context_get_client_info=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, PA_CLIENT_INFO_CB_T, c_void_p] ),
		pa_context_get_server_info=( 'pa_op',
			[POINTER(PA_CONTEXT), PA_SERVER_INFO_CB_T, c_void_p] ),
		pa_context_get_card_info_by_index=( 'pa_op',
			[POINTER(PA_CONTEXT), c_uint32, PA_CARD_INFO_CB_T, c_void_p] ),
		pa_context_get_card_info_by_name=( 'pa_op',
			[POINTER(PA_CONTEXT), c_str_p, PA_CARD_INFO_CB_T, c_void_p] ),