code: def has_mixture_channel(val: Any) -> bool:
      
      mixture_getter = getattr(val, '_has_mixture_', None)
      result = NotImplemented if mixture_getter is None else mixture_getter()
      if result is not NotImplemented:
          return result
  
      result = has_unitary(val)
      if result is not NotImplemented and result:
          return result
  
      # No _has_mixture_ or _has_unitary_ function, use _mixture_ instead.
      return mixture_channel(val, None) is not None
docs: Returns whether the value has a mixture channel representation.
  
      In contrast to `has_mixture` this method falls back to checking whether
      the value has a unitary representation via `has_channel`.
  
      Returns:
          If `val` has a `_has_mixture_` method and its result is not
          NotImplemented, that result is returned. Otherwise, if `val` has a
          `_has_unitary_` method and its results is not NotImplemented, that
          result is returned. Otherwise, if the value has a `_mixture_` method
          that is not a non-default value, True is returned. Returns False if none
          of these functions.