add_handler_capabilities
Description:
Add several capability tokens to this client.
These are used to signal that Telepathy connection managers should advertise certain capabilities to other contacts, such as the ability to receive audio/video calls using particular streaming protocols and codecs.
This method may only be called before register is called, and may only be called on objects whose class implements handle_channels.
Parameters:
| this |
a client, which must not have been registered with register yet |
| tokens |
capability tokens as defined by the Telepathy D-Bus API Specification |