const classafButter::ButterErrsys::Obj sys::Err afButter::ButterErrAs thrown by Butter.availableValuesSourceconst Str[]? availableValuesmakeSourcenew make(Str msg := "", Err? cause := null)makeFromValuesSourcenew makeFromValues(Str msg, Obj?[] availableValues, Err? cause := null)toStrSourcevirtual override Str toStr()