What does the following PLpgSQL function compute?

create or replace function

mystery$($n integer, m integer$)$ returns integer

as $$

declare

i integer;

r integer :$=1$;

begin

r :$=$ n;

for i in $2..$m loop

r :$=$ r $*$ n;

end loop;

return r;

end;

$$ language plpgsql;