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    User-defined Functions
                     Functions defined by the user according to the needs of the program are called user-defined

                     functions. They can perform a specific task. User-defined functions are called and used in the
                     same way as built-in functions.

                     CREATING A FUNCTION
                     The syntax to define a function is as follows:

                     def function_name(parameter1, parameter2,…,parameterN):
                         #function body

                         #return statement
                     A Python function consists of the following components:
                         The def keyword: Every function definition must begin with the def keyword.
                         Function  name: It comes  after the def keyword,  should be meaningful and follow  Python
                        naming rules.

                         Parameters: After the function’s name, parameters are defined inside parentheses. These are
                        optional and contain the variables that are passed to a function to perform a specific task.
                         Function body: It contains one or more indented code statements that execute when the
                        function is called.
                         The return keyword: The return keyword is used to exit a function.

                         Return statement: It is optional and is used if you want your function to return a value. If there
                        is no return statement, then the function will return None.
                     For example, to calculate the area of a rectangle, a function is:

                     def calculate_area(Length, Breadth):

                         area=Length*Breadth
                         return area

                     CALLING A FUNCTION

                     Once you have defined the function, you can call it from another function, program or even the
                     Python prompt. You can call a function by typing the function name followed by parentheses. If
                     the function takes any arguments, they are included within the parentheses.
                     The syntax to call a function is as follows:

                     function_name(parameter1,parameter2,…,parameterN)
                     For example, suppose you have a function named calculate_area() that takes two parameters,
                     length and breadth. You can execute it as follows:

                     def calculate_area(Length, Breadth):
                         area=Length*Breadth
                         return area

                     calculate_area(4, 5)

                                                                                                                      145
                                                                                                Step Ahead with Python

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