anchor.diff:    (Error_UncontrainedUnificationVar                  , CError);
     (Error_UnexpectedGTotComputation                   , CError);
     (Error_UnexpectedInstance                          , CError);
  -  (Error_BadImplicit                                 , CError);
     (Error_UnknownFatal_AssertionFailure               , CError);
     (Error_Z3InvocationError                           , CError);
     (Error_IDEAssertionFailure                         , CError);
  
positive.code:   (Warning_Z3InvocationWarning                       , CWarning);
    (Warning_MissingInterfaceOrImplementation          , CWarning);
    (Warning_ConstructorBuildsUnexpectedType           , CWarning);
    (Warning_ModuleOrFileNotFoundWarning               , CWarning)]
  
  exception Err of raw_error* string
  exception Error of raw_error * string * Range.range
  
negative.code:   | Error_UncontrainedUnificationVar
    | Error_UnexpectedGTotComputation
    | Error_UnexpectedInstance
    | Error_UnknownFatal_AssertionFailure
    | Error_Z3InvocationError
    | Error_IDEAssertionFailure
  