itemgetter

Used to get the elements in the array with the specified index

```from operator import itemgetter
itemgetter(1, 3, 5)('ABCDEFG')

output:
('B', 'D', 'F')
```

slice

Used to slice a list , It is also the element that gets the specified index

```a = slice(0,10,2)
b = list(range(10))
b[a]
b[0:10:2]
itemgetter(a)(b)

output:
[0, 2, 4, 6, 8]
[0, 2, 4, 6, 8]
[0, 2, 4, 6, 8]
```

and_ amount to a & b, To find the intersection of two sets

Can unite reduce Realize the calculation of the intersection of multiple sets

```from functools import reduce
from operator import and_
print(reduce(and_, [{1,2,3},{2,3,4},{3,4,5},{1,3,5}]))

output:
{3}
```

or_ amount to a | b, To find the intersection of two sets

Can unite reduce Realize the calculation of union of multiple sets

```from functools import reduce
from operator import or_
print(reduce(or_, [{1,2,3},{2,3,4},{3,4,5},{1,3,5}]))

output:
{1, 2, 3, 4, 5}
```

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