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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def token_setter(remote, token, secret='', token_type='', extra_data=None, user=None):
 """Set token for user. :param remote: The remote application. :param token: The token to set. :param token_type: The token type. (Default: ``''``) :param extra_data: Extra information. (Default: ``None``) :param user: The user owner of the remote token. If it's not defined, the current user is used automatically. (Default: ``None``) :returns: A :class:`invenio_oauthclient.models.RemoteToken` instance or ``None``. """

    session[token_session_key(remote.name)] = (token, secret)
    user = user or current_user

    # Save token if user is not anonymous (user exists but can be not active at
    # this moment)
    if not user.is_anonymous:
        uid = user.id
        cid = remote.consumer_key

        # Check for already existing token
        t = RemoteToken.get(uid, cid, token_type=token_type)

        if t:
            t.update_token(token, secret)
        else:
            t = RemoteToken.create(
                uid, cid, token, secret,
                token_type=token_type, extra_data=extra_data
            )
        return t
    return None