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