my $foo = do { local $/; <$fh> };

##</code><code>##

baz = (one two,
 three four,
 five six)

##</code><code>##

baz = (one two, three four, five six)

##</code><code>##

while ($foo =~ s/(\([^)]*)\n(.*?\))/$1$2/gs) {}