sequence types set types mapping types iterating and copying collections collection data types |||in the preceding we learned about python' most important fundamental data types in this we will extend our programming options by learning how to gather data items together using python' collection data types we will cover tuples and listsand also introduce new collection data typesincluding sets and dictionariesand cover all of them in depth in addition to collectionswe will also see how to create data items that are aggregates of other data items (like or +structs or pascal records)--such items can be treated as single unit when this is convenient for uswhile the items they contain remain individually accessible naturallywe can put aggregated items in collections just like any other items having data items in collections makes it much easier to perform operations that must be applied to all of the itemsand also makes it easier to handle collections of items read in from files we'll cover the very basics of text file handling in this as we need themdeferring most of the detail (including error handlingto after covering the individual collection data typeswe will look at how to iterate over collectionssince the same syntax is used for all of python' collectionsand we will also explore the issues and techniques involved in copying collections ||sequence types sequence type is one that supports the membership operator (in)the size function (len())slices ([])and is iterable python provides five built-in sequence typesbytearraybytesliststrand tuple--the first two are covered the definitions of what constitutes sequence typea set typeor mapping type given in this are practical but informal more formal definitions are given in