The value returned is a list of pairs of integers corresponding to the parenthesized subexpressions successfully matched. If no matching substring was found, then
null is returned. The first member of each pair is the offset within
s of the substring matched, and the second is the length.
i1 : regex("a",0,"a b c a")
o1 = {(0, 1)}
o1 : List
|
i2 : regex("a",1,"a b c a")
o2 = {(6, 1)}
o2 : List
|