'A body type of type TEXT contains, immediately after the basic
fields, the size of the body in text lines.  Note that this
size is the size in its content transfer encoding and not the
resulting size after any decoding.'

def encode(self, extended):

    result = _SinglepartMessageStructure._basicFields(self)
    result.append(getLineCount(self.message))
    if extended:
        result.extend(self._extended())
    return result
