vCset cs = c.mkCset();
vCset cs = a.mkCset();
        public vDescriptor Call(	    vDescriptor a, vDescriptor b, vDescriptor c, vDescriptor d) {	vCset cs = c.mkCset();	vString s = fScan.subj(b);	int i1 = s.posEq(fScan.pos(b, c));	int i2 = s.posEq(d.isnull() ? 0 : d.mkInteger().value);	if (i1 == 0 || i2 == 0) {	    return null;	}	if (i1 > i2) {	    int tmp = i1;	    i1 = i2;	    i2 = tmp;	}	if (i1 >= i2) {	    return null;	}	byte t[] = s.getBytes();	int i;	for (i = i1; i < i2; i++) {	    if (!cs.member(t[i-1])) {		break;	    }	}	if (i == i1) {	    return null;	} else {	    return vInteger.New(i);	}    }