E1:     C1 CALL pred catch.main/2-0 (cc_multi) catch.m:8
mdb> echo on
Command echo enabled.
mdb> register --quiet
mdb> break p
 0: + stop  interface pred catch.p/2-0 (cc_multi)
mdb> continue
      E2:     C2 CALL pred catch.p/2-0 (cc_multi) catch.m:18 (catch.m:9)
mdb> finish
      E3:     C2 EXIT pred catch.p/2-0 (cc_multi) catch.m:18 (catch.m:9)
mdb> dd -d 3 -n 7
p(1, exception(univ_cons("q: bad input")))
Valid? no
Sorry, the diagnosis cannot continue because it requires support for
the following: code that catches exceptions.
The debugger is a work in progress, and this is not supported in the
current version.
      E3:     C2 EXIT pred catch.p/2-0 (cc_multi) catch.m:18 (catch.m:9)
mdb> continue
exception(univ_cons("q: bad input"))
      E4:     C3 CALL pred catch.p/2-0 (cc_multi) catch.m:18 (catch.m:12)
mdb> finish
      E5:     C3 EXIT pred catch.p/2-0 (cc_multi) catch.m:18 (catch.m:12)
mdb> dd -d 3 -n 7
p(2, succeeded(2))
Valid? no
q(2, 2)
Valid? yes
Found incorrect contour:
try(q(2), succeeded(2))
p(2, succeeded(2))
Is this a bug? yes
      E5:     C3 EXIT pred catch.p/2-0 (cc_multi) catch.m:18 (catch.m:12)
mdb> continue
succeeded(2)