Multi line parameter value?

I don't suppose it's possible to specify a parameter with a multi line
value.

My use case is that I have a macro that groups over an alias, and I would
like to not hard-code what aggregate values I compute.

If I could pass in a multi line parameter value, I would be able to do
something like:

set my_param = 'SUM(foo) as bar, \
SUM (bazz) as boo';

my_alias = compute_aggreate(some_alias, my_param);