parse_tracks_file: validate_line call is missing a required argument "line_number"

[chaps]

The call of "validate_line" inside the parse_tracks_file function , is missing the required "line_number" argument:

Traceback (most recent call last):
  File "/.../bin/lobster", line 7, in <module>
    exec(compile(f.read(), __file__, 'exec'))
  File "/.../bin/lobster", line 49, in <module>
    generate_album(**kwargs)
  File "/.../bin/lobster", line 26, in generate_album
    audio_segments = parse_tracks_file(tracks)
  File "/.../lobster/parser.py", line 19, in parse_tracks_file
    validate_line(_d)
TypeError: validate_line() missing 1 required positional argument: 'line_number'