A set is used to contain an unordered collection of objects. To create a set, use the `set()` function and supply a sequence of items such as follows:

s = set([3,5,9,10]) # Create a set of numbers t = set("Hello") # Create a set of characters

Unlike lists and tuples, sets are unordered and cannot be indexed in the same way. More over, the elements of a set are never duplicated. For example, if you print the value of `t` from the preceding code, you get the following:

>>> print t set(['H', 'e', 'l', 'o'])

Notice that only one `'l'` appears.

Sets support a standard collection of set operations, including union, intersection, difference, and symmetric difference. For example:

a = t | s # Union of t and s b = t & s # Intersection of t and s c ...

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