You have an older version of the RM4 Pro. The newer models are not supported yet until the dev has released python-broadlink v.0.18.1.
Support for device: 0x5213 is already implemented with the not yet released v.0.18.1. With a little bit of experience you can add device: 0x5213 by yourself though.
Which Broadlink model do you want to add? As for the Broadlink RM4Pro with device code 0x5213: (“RM4 pro”, “Broadlink”) this is already added to the official code since version 0.18.1.