SOURCELINE

 ──SOURCELINE(─┬─────┬─)──────
                 └──n──┘

SOURCELINE returns the line number of the final line in the source file if you omit n, or returns the n th line in the source file if you specify n.

If specified, n must be a positive whole number, and must not exceed the number of the final line in the source file.

Here are some examples:

SOURCELINE()    ->   10
SOURCELINE(1)   ->   '/* This is a 10-line program */'