E1:     C1 CALL pred remember_modes.main/2-0 (det) remember_modes.m:34
mdb> Contexts will not be printed.
mdb> mdb> echo on
Command echo enabled.
mdb> break q
 0: + stop  interface pred remember_modes.q/5-0 (semidet)
mdb> continue
      E2:     C2 CALL pred remember_modes.q/5-0 (semidet)
mdb> finish
      E3:     C2 EXIT pred remember_modes.q/5-0 (semidet)
mdb> dd -d 3 -n 7
q(1, 1, 2, 1, 2)
Valid? no
p(1, 2)
Valid? yes
Found incorrect contour:
p(1, 2)
p(1, 2)
p(1, 2)
p(1, 2)
q(1, 1, 2, 1, 2)
Is this a bug? yes
      E3:     C2 EXIT pred remember_modes.q/5-0 (semidet)
mdb> continue
1
2
1
2