[Kc] Scalar + Shift?

[djgoku]

So I was looking at Net::IRC irctest file which is given  as a
"working bot" example and seen something I don't get (my $scalar =
shift;) and haven't seen a comment explaining why this done. The only
thing I can come up with it shifts off $scalar and makes it
empty/"clears any value"/undef right?

Looking at more examples uses of modules on cpan.org they're are also
shifting scalars.

perldoc -f shift #Says nothing about shifting scalar variables.