after thatyou can use it in expressions with other variables and values when variable is assigned new value the old value is forgottenwhich is why spam evaluated to instead of at the end of the example this is called overwriting the variable enter the following code into the interactive shell to try overwriting stringspam 'hellospam 'hellospam 'goodbyespam 'goodbyejust like the box in figure - the spam variable in this example stores 'hellountil you replace the string with 'goodbyefigure - when new value is assigned to variablethe old one is forgotten variable names good variable name describes the data it contains imagine that you moved to new house and labeled all of your moving boxes as stuff you' never find anythingmost of this book' examples (and python' documentationuse generic variable names like spameggsand baconwhich come from the monty python "spamsketch but in your programsa descriptive name will help make your code more readable