 /// Member access operations return an `Optional` result. When member access
 /// fails, `nil` is returned.
 @dynamicMemberLookup
-@frozen
 public struct CheckingPythonObject {
   /// The underlying `PythonObject`.
   private var base: PythonObject

}

/// An error produced by a failable Python operation.
@frozen
public enum PythonError : Error, Equatable {
  /// A Python runtime exception, produced by calling a Python function.
  case exception(PythonObject, traceback: PythonObject?)

///   `@dynamicCallable` attribute because the call syntax is unintuitive:
///   `x.throwing(arg1, arg2, ...)`. The methods will still be named
///   `dynamicallyCall` until further discussion/design.
public struct ThrowingPythonObject {
  private var base: PythonObject

