'Post a twitter direct message from the authenticated user
The twitter.Api instance must be authenticated.
Args:
user: The ID or screen name of the recipient user.
text: The message text to be posted.  Must be less than 140 characters.
Returns:
A twitter.DirectMessage instance representing the message posted'

def PostDirectMessage(self, user, text):

    if (not self._username):
        raise TwitterError('The    twitter.Api    instance    must    be    authenticated.')
    url = (TWITTER_API_ROOT + 'direct_messages/new.json')
    data = {'text': text, 'user': user}
    json = self._FetchUrl(url, post_data=data)
    data = simplejson.loads(json)
    self._CheckForTwitterError(data)
    return DirectMessage.NewFromJsonDict(data)
