Pulls out all the symbols from descriptor protos.

    Args:
      descriptors: The messages to extract descriptors from.
    Yields:
      A two element tuple of the type name and descriptor object.

def _ExtractSymbols(self, descriptors):
    """Pulls out all the symbols from descriptor protos.

    Args:
      descriptors: The messages to extract descriptors from.
    Yields:
      A two element tuple of the type name and descriptor object.
    """

    for desc in descriptors:
      yield (_PrefixWithDot(desc.full_name), desc)
      for symbol in self._ExtractSymbols(desc.nested_types):
        yield symbol
      for enum in desc.enum_types:
        yield (_PrefixWithDot(enum.full_name), enum)