Genius class should automatically check for token environment variable

Is your feature request related to a problem? Please describe. No problem, it’s just a hassle to retrieve your client access token from os each time you use lyricsgenius.

Describe the solution you’d like If the user doesn’t pass a user token to Genius, the class should check the OS environment variables for GENIUS_ACCESS_TOKEN.

Describe alternatives you’ve considered There are no alternatives.

Additional context Probably here is where you’d modify the code.

[allerter]

The only case that could lead to confusion is that if the user passes no token, but has an invalid token in their env var, and then tries to use an endpoint using the developers API. Should we print a message in that case? Something like this:

if token is None:
    token = os.environ.get("GENIUS_ACCESS_TOKEN")
    if token is not None:
        print("Token was obtained from environment variables.")
self.access_token = token

[allerter]

It’s probably better for the package to rely on the API as much as possible as you said. And since the token-less branch is complete, I’ll just leave it on my fork. I’ll update #162 soon.