text: #include "test_framework/generic_test.h"
  unsigned long long ReverseBits(unsigned long long x) {
    constexpr auto kSize = sizeof(x) * 8;
  
    auto result = 0ull;
  
    for (int i = 0; i < kSize; ++i) {
      result <<= 1u;
      result |= x & 1u;
      x >>= 1u;
    }
  
    return result;
  }
  
  int main(int argc, char* argv[]) {
    std::vector<std::string> args{argv + 1, argv + argc};
    std::vector<std::string> param_names{"x"};
    return GenericTestMain(args, "reverse_bits.cc", "reverse_bits.tsv",
                           &ReverseBits, DefaultComparator{}, param_names);
  }
  