<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def sign(uri, headers, credentials):
 """Sign the URI and headers. A request method of `GET` with no body content is assumed. :param credentials: A tuple of consumer key, token key, and token secret. """

    consumer_key, token_key, token_secret = credentials
    auth = OAuthSigner(token_key, token_secret, consumer_key, "")
    auth.sign_request(uri, method="GET", body=None, headers=headers)