Which of the following identifiers are valid? Which are Python keywords (see Appendix A)?
miles, Test, a+b, b–a, 4#R, $4, #44, apps
if, elif, x, y, radius
Valid identifiers: miles, Test, apps, x, y, radius
Invalid identifiers: a+b, b-a, 4#R, $4, #44
Keywords:if, elif