docs: def extend(self, iterable):
          """ Extends the `Sequence` by appending items from the *iterable*.
  
          :param iterable: any *iterable* that contains items of :class:`Structure`,
              :class:`Sequence`, :class:`Array` or :class:`Field` instances. If the
              *iterable* is one of these instances itself then the *iterable* itself
              is appended to the `Sequence`.
          """
          # Sequence
          if is_sequence(iterable):
              self._data.extend(iterable)
          # Structure
          elif is_structure(iterable):
              members = [item for item in iterable.values()]
              self._data.extend(members)
          # Field
          elif is_field(iterable):
              self._data.extend([iterable])
          # Iterable
          elif isinstance(iterable, (set, tuple, list)):
              self._data.extend(Sequence(iterable))
          else:
              raise MemberTypeError(self, iterable, member=len(self))