How to get warnings for unused parts of a file?

[Omid Mo'menzadeh]

Hello all. This might be a weird thing to seek, but here is the scenario:

I have several files defining (but not using) different parts of the score, which other files use to construct several output types.

But the problem is the command `lilypond -l WARNING -o /path/to/file.ly` does not show a warning for the following example file:

ghigh = \relative c {
  \clef "treble_8"
  \time 4/4
  \voiceOne
  c2 |
}

It does, if I include the following part at the end of the file:

\book {
  \ghigh
}

But the problem is that when I include it in another file, I get an extra output!

A possible solution could look like an `if __name__ == "__main__"` clause in Python, but I don't know if we have a similar variable available in Lilypond.

Thanks in advance,

Omid