uint32 a
uint32 b
uint32 c

string sa
string sb
string sc

#
#  b is missing, so its default value is 0
#
a = 1
c = a - b

if !(c == a) {
	test_fail
}

sa = "foo"
sc = sa + sb

#
#  sb is missing, so its default value is the empty string
#
if !(sc == sa) {
	test_fail
}
success
