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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 create_cas_login_url(cas_url, cas_route, service, renew=None, gateway=None):
 """ Create a CAS login 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) service -- (ex. http://localhost:5000/login) renew -- "true" or "false" gateway -- "true" or "false" Example usage: 'http://sso.pdx.edu/cas?service=http%3A%2F%2Flocalhost%3A5000' """

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