yes, that's a part of a solution, but it's not doing the main job: parsing a string of parameters and quoting them. It just quotes one parameter.

See:
ls a b c
is transformed into
ls 'a b c'
which results in ls: a b c: No such file or directory

Useful? No :-) And splitting by spaces won't help, e.g.
ls "a' b" c gives
ls '"a'\' 'b"' 'c' instead of
ls 'a'\'' b' 'c'