'Returns a single user.
The twitter.Api instance must be authenticated.
Args:
user: The username or id of the user to retrieve.
Returns:
A twitter.User instance representing that user'

def GetUser(self, user):

    url = (TWITTER_API_ROOT + ('users/show/%s.json' % user))
    json = self._FetchUrl(url)
    data = simplejson.loads(json)
    self._CheckForTwitterError(data)
    return User.NewFromJsonDict(data)
