YAML isn't part of the Python standard library, while JSON is.
If we want `setup.py` to dynamically parse the available integration
manifest files in order to populate the extra dependencies, then it's
better to rely on a JSON format for manifest files - the parser is part
of the standard library and it doesn't require the user to install
`pyyaml` before `platypush`.
1. I no longer I use a Spotify account (I switched to Tidal after
Spotify deprecated libspotify), and I wouldn't like to create one
just to test this integration.
2. After a couple of years, the libspotify open fork (Librespot) seems
to be still in an unstable stage and it's already been discontinued
once - I would avoid rebuilding the integration against a dependency
that may change a lot in the near future.
To be consistent with all other media plugins, the parameter name should
be `step`, not `delta`.
A back-compatibility layer has however been introduced for plugins
(namely `music.mpd` and `music.spotify`) that already exposed the old
interface.
Fabio Manganiello