<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def create_cas_validate_url(cas_url, cas_route, service, ticket, renew=None):
 """ Create a CAS validate URL. Keyword arguments: cas_url -- The url to the CAS (ex. http://sso.pdx.edu) cas_route -- The route where the CAS lives on server (ex. /cas/serviceValidate) service -- (ex. http://localhost:5000/login) ticket -- (ex. 'ST-58274-x839euFek492ou832Eena7ee-cas') renew -- "true" or "false" Example usage: 'http://sso.pdx.edu/cas/serviceValidate?service=http%3A%2F%2Flocalhost%3A5000%2Flogin&ticket=ST-58274-x839euFek492ou832Eena7ee-cas' """

    return create_url(
        cas_url,
        cas_route,
        ('service', service),
        ('ticket', ticket),
        ('renew', renew),
    )