sub foo {
	my @x = ("a", @_, "b"); # interpolation
	return "x", @x, "y";    # interpolation
}
my @y = ("i", "j");
my @z = foo("r", @y, "s");  # interpolation
# @z is ("x", "a", "r", "i", "j", "s", "b", "y")

# also: comma operator in scalar context via "return"
my $x = foo("u", "v");
# $x is "y" !!