Closures:
=========

what is closure?
================
def fun1(): # outer function
	def fun2(): # inner function
		implementation

==> closure is a nested function
which has access to a variable from an enclosing function that has finished its execution.
==> A variables which want access with the enclosed function is not bound to the local scope.
==> To use immutable variable (number, string, Boolean etc.), we have to use the "non-local" keyword.


Advantage of Closure:
=====================
1) we can help to avoid the using global values and provide some form the data hiding.
2) Can use in decorators.

Nested Function:
================
def fun1():
    print("This is the outer function")
    def fun2():
        print("This is the inner function")
    print("Hi")
    print("Good Morning")
    print("Welcome To Ashok IT")
    fun2()

fun1()

Variable Scope:
===============

def outer(p):
    q = 100
    def inner(r):
        return p + q + r
    return inner

cl = outer(112)
result = cl(121)

print(result)

=====================================

def fun1(name):# name = "Python"
    name = "Ashok IT" # modification of parameter value
    def fun2():
        print(name)
    return fun2

result = fun1("Python") # result = fun2 function aliasing
result()

========================================

nonlocal keyword:
=================
==> this allows a variable outside the local scope to be accessed.
==> can use in closures.
	to modify an immutable variable present in the scope of outer variable.

def f1():
    counter = 0 # immutable
    def f2():
        nonlocal counter
        counter = counter + 1
        return counter
    return f2

closure = f1() # function aliasing
result = closure()

print("Result = ",result)

result = closure()

print("Result = ",result)

result = closure()

print("Result = ",result)

result = closure()

print("Result = ",result)