yeah from tryto.h it imports expected.h, which has the following methods in the value and error getters:

inline void verifyIsError() const {
    debug_only::verify([this]() { return object_.which() == kErrorType_; },
                       "Do not try to get error from Expected with value");
  }

  inline void verifyIsValue() const {
    debug_only::verify([this]() { return object_.which() == kValueType_; },
                       "Do not try to get value from Expected with error");
  }