Returns the number of days left until an evaluation license expires.

The following calls getdaysleft to print information about the license:

try:
    ndays = xpress.getdaysleft()
except RuntimeError:
    print("Not an evaluation license")
else
    print("Evaluation license expires in {0} days".format(ndays))

This function can only be used with evaluation licenses, and, if called when a normal license is in use, it returns an error. The expiry information for evaluation licenses is also included in the Optimizer banner message.