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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 userinfo_in_id_token_claims(endpoint_context, session, def_itc=None):
 """ Collect user info claims that are to be placed in the id token. :param endpoint_context: Endpoint context :param session: Session information :param def_itc: Default ID Token claims :return: User information or None """

    if def_itc:
        itc = def_itc
    else:
        itc = {}

    itc.update(id_token_claims(session))

    if not itc:
        return None

    _claims = by_schema(endpoint_context.id_token_schema, **itc)

    if _claims:
        return collect_user_info(endpoint_context, session, _claims)
    else:
        return None