How to open a closure in python?

The function cons takes two arguments, a and b, and returns a function that takes one argument, f. The returned function is a closure, since it contains references to a and b which would otherwise be out of scope when cons returns.

The returned function takes a function argument, calls it with a and b, and returns the result.

For example, if you do:

func = cons(6, 8)

Then you can do:

def g(a, b):
    return a

func(g)

This will return 6. Similarly, if you define g to return b, then func would return 8.

you can try:

pair = cons(6, 8)

def first(pair):
    return  pair(lambda x, y: x)

def second(pair):
    return  pair(lambda x, y: y)

print(first(pair))
print(second(pair))

# ouput:
# 6
# 8