Re: [Libguestfs] [PATCH v3 4/8] mllib: Add some imperative list manipulation functions.

This adds imperative list manipulation functions inspired by Perl. The functions are passed list refs which get updated in place. This allows us to replace some awkward pure functional code like: let xs = ys in let xs = if foo then xs @ zs else xs in with: let xs = ref ys in if foo then append xs zs; ---