LD_PRELOAD=./libhandle_contract_violation.so ./assert_fail
contract violation: assert_fail.cpp:3: fun1::x < 0 is false [with contract level=default]
violation occurs here:
    assert_fail.cpp:fun1():4
    assert_fail.cpp:tns::fun2():8
    assert_fail.cpp:void fun3<int>(int):13
    assert_fail.cpp:fun4():16
    assert_fail.cpp:main:21