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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 express_endpoint_for_token(token, commit=False):
 """ Returns the PayPal Express Checkout endpoint for a token. Pass 'commit=True' if you will not prompt for confirmation when the user returns to your site. """

    pp_params = dict(token=token)
    if commit:
        pp_params['useraction'] = 'commit'
    return express_endpoint() % urlencode(pp_params)