Você não pode usar a API do tweepy sem registrar suas credenciais.
Tweepy tries to make OAuth as painless as possible for you. To begin the process we need to register our client application with Twitter. Create a new application and once you are done you should have your consumer token and secret. Keep these two handy, you’ll need them.
Veja este exemplo código:
from __future__ import absolute_import, print_function
import tweepy
# == OAuth Authentication ==
#
# This mode of authentication is the new preferred way
# of authenticating with Twitter.
# The consumer keys can be found on your application's Details
# page located at https://dev.twitter.com/apps (under "OAuth settings")
consumer_key=""
consumer_secret=""
# The access tokens can be found on your applications's Details
# page located at https://dev.twitter.com/apps (located
# under "Your access token")
access_token=""
access_token_secret=""
auth = tweepy.OAuthHandler(consumer_key, consumer_secret)
auth.secure = True
auth.set_access_token(access_token, access_token_secret)
api = tweepy.API(auth)
# If the authentication was successful, you should
# see the name of the account print out
print(api.me().name)
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