def add_prompt(self, prompt, echo=True):
self.prompts.append((prompt, echo))<EOL>
Add a prompt to this query.  The prompt should be a (reasonably short)
string.  Multiple prompts can be added to the same query.

:param str prompt: the user prompt
:param bool echo:
    ``True`` (default) if the user's response should be echoed;
    ``False`` if not (for a password or similar)