rapid introduction to procedural programming difference if computing the data item' value is expensiveor if accessing the data item causes side effects thanks to the "strongaspect of python' dynamic typingcomparisons that don' make sense will cause an exception to be raised for example"three traceback (most recent call last)typeerrorunorderable typesstr(int(when an exception is raised and not handledpython outputs traceback along with the exception' error message for claritywe have omitted the traceback part of the outputreplacing it with an ellipsis the same typeerror exception would occur if we wrote " because python does not try to guess our intentions--the right approach is either to explicitly convertfor exampleint(" " or to use comparable typesthat isboth integers or both strings python makes it easy for us to create custom data types that will integrate nicely so thatfor examplewe could create our own custom numeric type which would be able to participate in comparisons with the built-in int typeand with other built-in or custom numeric typesbut not with strings or other non-numeric types the membership operator for data types that are sequences or collections such as stringslistsand tupleswe can test for membership using the in operatorand for nonmembership using the not in operator for examplep ( "frog" - in true "dognot in true for lists and tuplesthe in operator uses linear search which can be slow for very large collections (tens of thousands of items or moreon the other handin is very fast when used on dictionary or setboth of these collection data types are covered in here is how in can be used with stringphrase "wild swans by jung chang"jin phrase true traceback (sometimes called backtraceis list of all the calls made from the point where the unhandled exception occurred back to the top of the call stack dealing with runtime errors alternative fuzzybool