Can you call a function in a function python?

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Prerequisite: Functions in Python
In Python, any written function can be called by another function. Note that this could be the most elegant way of breaking a problem into chunks of small problems. In this article, we will learn how can we call a defined function from another function with help of multiple examples. 

Calling and Called Function ? 
The Function which calls another Function is called Calling Function and function which is called by another Function is call Called Function.

How does Function execution work? 
A stack data structure is used during the execution of the function calls. Whenever a function is invoked then the calling function is pushed into the stack and called function is executed. When the called function completes its execution and returns then the calling function is popped from the stack and executed. Calling Function execution will be completed only when called Function is execution completes.

In the below figure. The function call is made from the Main function to Function1, Now the state of the Main function is stored in Stack, and execution of the Main function is continued when the Function 1 returns. The Fucntion1 Calls Function2 now the State of the Function1 is stored stack and execution of Function 1 will be continued when Function 2 returns. 

Consider the below Example of the function call. The Function SumOfSquares function calls the Function Square which returns the square of the number. 

Python3

def Square(X):

    return (X * X)

def SumofSquares(Array, n):

    Sum = 0

    for i in range(n):

        SquaredValue = Square(Array[i])

        Sum += SquaredValue

    return Sum

Array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

n = len(Array)

Total = SumofSquares(Array, n)

print("Sum of the Square of List of Numbers:", Total)

Output : 

Sum of the Square of List of Numbers: 385 

Calling Function From another Function within Same class –
In the below example, the class method Function1 calls method Function2 from the class.

Python3

class Main:

    def __init__(self):

        self.String1 ="Hello"

        self.String2 ="World"

    def Function1(self):

        self.Function2()

        print("Function1 : ", self.String2)

        return

    def Function2(self):

        print("Function2 : ", self.String1)

        return

Object = Main()

Object.Function1()

Output : 

Function2 :  Hello
Function1 :  World

Calling parent class Function from Child class Function –
Consider the below example the child class method invokes the parent class method. The child class inherits the attributes from the parent class.

Python3

class Parent:

    def __init__(self):

        self.String1 ="Hello"

        self.String2 ="World"

    def Function2(self):

        print("Function2 : ", self.String1)

        return

class Child(Parent):

    def Function1(self):

        self.Function2()

        print("Function1 : ", self.String2)

        return  

Object1 = Parent()

Object2 = Child()

Object2.Function1()

Output : 

Function2 :  Hello
Function1 :  World