user@localhost:~/travel$ klee-go travel.c 
travel.c:52:2: warning: implicit declaration of function '__assert_fail' is invalid in
      C99 [-Wimplicit-function-declaration]
        klee_assert(!ham_cycle(cycle));
        ^
../klee/include/klee/klee.h:96:6: note: expanded from macro 'klee_assert'
   : __assert_fail (#expr, __FILE__, __LINE__, __PRETTY_FUNCTION__))    \
     ^
1 warning generated.
KLEE: NOTE: Using klee-uclibc : /home/user/klee/Release+Asserts/lib/klee-uclibc.bca
KLEE: NOTE: Using model: /home/user/klee/Release+Asserts/lib/libkleeRuntimePOSIX.bca
KLEE: output directory is "/home/user/travel/klee-out-3"
Using STP solver backend
KLEE: WARNING: undefined reference to function: klee_posix_prefer_cex
KLEE: WARNING ONCE: calling external: syscall(16, 0, 21505, 47742720)
KLEE: ERROR: /home/user/travel/travel.c:52: ASSERTION FAIL: !ham_cycle(cycle)
KLEE: NOTE: now ignoring this error at this location

KLEE: done: total instructions = 2568
KLEE: done: completed paths = 16
KLEE: done: generated tests = 16

ktest file : 'klee-last/test000015.ktest'
args       : ['travel.bc']
num objects: 2
object    0: name: 'model_version'
object    0: size: 4
object    0: data: '\x01\x00\x00\x00'
object    1: name: 'cycle'
object    1: size: 6
object    1: data: '\x04\x02\x03\x00\x01\x04'