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    User-Defined Functions
                     User-defined functions are created by the user according to the need of the program. Once the
                     user defines a function, the user can call it in the same way as the built-in functions.
                     The main difference between these two categories is that built-in functions do not require to
                     be written by us, whereas a user-defined functions are created by the programmer to address
                     specific requirements or perform custom tasks within a program.

                     CREATING A FUNCTION
                     We can create a function in the following ways:

                       Defining a Function: We use the def keyword to begin the function definition.
                       Naming a Function: Provide a meaningful name to your function.

                       Parameters: The parameters (separated by commas) are specified within the parenthesis
                       following the name of the function. These are basically the input values we pass to the function.
                       Body of the Function: The body of the function contains Python statements that make our
                       function perform the required task.
                       The syntax of creating a function is as follows:

                       def < name of the function > (list of parameters)

                                 <body>
                     CALLING A FUNCTION

                     A function can be called anytime from other functions or from the command prompt after the
                     definition. For calling a function, we type the function and pass the parameters. For example:
                     To call a function

                                    def my_function()                                    Name of a function

                                          print (“Hello”)                                Body of a function

                                    my_function()                                         Function call

                     Program 1: To print a string by calling a function
                         Program1.py

                      File  Edit  Format   Run    Options  Window     Help

                      #Function definition
                      def hello (name):
                          print('Hello ' +name+ '! How do you do?')

                      #Calling function by passing parameter
                      hello('Orange')

                                                                                       Functions, String and List in Python  91

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