Types of Python Function Arguments
Python supports various types of arguments that can be passed at the time of the function call. In Python, we have the following 4 types of function arguments.
1.Default argument
2.Keyword arguments (named arguments)
3.Positional arguments
4.Arbitrary arguments (variable-length arguments *args and **kwargs)

Let’s discuss each type in detail. 

1. Default Arguments
A default argument is a parameter that assumes a default value if a value is not provided in the function call for that argument. The following example illustrates Default arguments. 
# Python program to demonstrate

 

# default arguments
def myFun(x=30, y=50):
    print("x: ", x)
    print("y: ", y)
# Driver code (We call myFun() with only
# argument)
myFun(10)

 
OUTPUT


 

  2.Keyword Arguments
The idea is to allow the caller to specify the argument name with values so that the caller does not need to remember the order of parameters.

 

# Python program to demonstrate Keyword Arguments
def student(firstname, lastname):
    print(firstname, lastname)
# Keyword arguments
student(firstname='Geeks', lastname='Practice')
student(lastname='Practice', firstname='Geeks')

 
OUTPUT


 

  3.Positional Arguments
We used the Position argument during the function call so that the first argument (or value) is assigned to name and the second argument (or value) is assigned to age. By changing the position, or if you forget the order of the positions, the values can be used in the wrong places, as shown in the Case-2 example below, where 27 is assigned to the name and Suraj is 
assigned to the age.

 

def nameAge(name, age):
    print("Hi, I am", name)
    print("My age is ", age)
# You will get correct output because
# argument is given in order
print("Case-1:")
nameAge("Suraj", 27)
# You will get incorrect output because
# argument is not in order
print("\nCase-2:")
nameAge(27, "Suraj")

 
OUTPUT


 

  4. Arbitrary Keyword  Arguments
In Python Arbitrary Keyword Arguments, *args, and **kwargs can pass a variable number of arguments to a function using special symbols. There are two special symbols:

*args in Python (Non-Keyword Arguments)
**kwargs in Python (Keyword Arguments)
Example 1: Variable length non-keywords argument

 

# Python program to illustrate
# *args for variable number of arguments
def myFun(*argv):
    for arg in argv:
        print(arg)
myFun('Hello', 'Welcome', 'to', 'GeeksforGeeks')

 
OUTPUT


 

  Example 2: Variable length keyword arguments.

 

# Python program to illustrate
# *kwargs for variable number of keyword arguments
def myFun(**kwargs):
    for key, value in kwargs.items():
        print("%s == %s" % (key, value))
# Driver code
myFun(first='Geeks', mid='for', last='Geeks')

 
OUTPUT


 

  Docstring:-
The first string after the function is called the Document string or Docstring in short. This is used to describe the functionality of the function. The use of docstring in functions is optional but it is considered a good practice.

The below syntax can be used to print out the docstring of a function:
Syntax: print(function_name.__doc__)
Example: Adding Docstring to the function

 

# A simple Python function to check
# whether x is even or odd
def evenOdd(x):
    """Function to check if the number is even or odd"""
     
    if (x % 2 == 0):
        print("even")
    else:
        print("odd")
# Driver code to call the function
print(evenOdd.__doc__)

 
OUTPUT
Function to check if the number is even or odd

 

  Python Function within Functions
A function that is defined inside another function is known as the inner function or nested function. Nested functions are able to access variables of the enclosing scope. Inner functions are used so that they can be protected from everything happening outside the function.

 

# Python program to
# demonstrate accessing of
# variables of nested functions
def f1():
    s = 'I love GeeksforGeeks'
         def f2():
        print(s)
            f2()
# Driver's code
f1()

 
OUTPUT
I love GeeksforGeeks