pragma experimental SMTChecker;library L
{functionadd(uint x,uint y)internal pure returns(uint) {require(x <1000);require(y <1000);return x + y;}}contract C
{using L foruint;functionf(uint x)public pure{uint y = x.add(999);assert(y <1000);}}// ----// Warning: (261-277): Assertion violation happens here