import semver class VersionConstraint: def is_empty(self): # type: () -> bool raise NotImplementedError() def is_any(self): # type: () -> bool raise NotImplementedError() def allows(self, version): # type: (semver.Version) -> bool raise NotImplementedError() def allows_all(self, other): # type: (VersionConstraint) -> bool raise NotImplementedError() def allows_any(self, other): # type: (VersionConstraint) -> bool raise NotImplementedError() def intersect(self, other): # type: (VersionConstraint) -> VersionConstraint raise NotImplementedError() def union(self, other): # type: (VersionConstraint) -> VersionConstraint raise NotImplementedError() def difference(self, other): # type: (VersionConstraint) -> VersionConstraint raise NotImplementedError()