partial orderbut not total orderas disjoint sets are neither "less than,"equal to,or "greater thaneach other sets also support many fundamental behaviors through named methods ( addremove)we will explore their functionality more fully in dictionarieslike setsdo not maintain well-defined order on their elements furthermorethe concept of subset is not typically meaningful for dictionariesso the dict class does not support operators such as dictionaries support the notion of equivalencewith = if the two dictionaries contain the same set of keyvalue pairs the most widely used behavior of dictionaries is accessing value associated with particular key with the indexing syntaxd[kthe supported operators are as followsd[keyd[keyvalue del [keykey in key not in = ! value associated with given key set (or resetthe value associated with given key remove key and its associated value from dictionary containment check non-containment check is equivalent to is not equivalent to dictionaries also support many useful behaviors through named methodswhich we explore more fully in extended assignment operators python supports an extended assignment operator for most binary operatorsfor exampleallowing syntax such as count + by defaultthis is shorthand for the more verbose count count for an immutable typesuch as number or stringone should not presume that this syntax changes the value of the existing objectbut instead that it will reassign the identifier to newly constructed value (see discussion of figure howeverit is possible for type to redefine such semantics to mutate the objectas the list class does for the +operator alpha [ beta alpha beta +[ beta beta [ print(alphaan alias for alpha extends the original list with two more elements reassigns beta to new list [ will be [ this example demonstrates the subtle difference between the list semantics for the syntax beta +foo versus beta beta foo