Python function
A function is a reusable block of code that performs a specific task or set of tasks. Functions are essential for organizing and modularizing your code, making it more readable, maintainable, and efficient.
Need for functions:
1. Code Reusability: Functions allow you to reuse code, reducing duplication and making programs more efficient.
2. Abstraction: Functions provide a higher-level view of operations, simplifying complex processes and improving code readability.
3. Modularity: Functions break down programs into manageable modules, enhancing design and maintenance.
4. Parameterization: Functions accept parameters, making them adaptable for different scenarios and data.
5. Encapsulation: Functions encapsulate functionality, enabling changes within a function's scope without affecting the rest of the code.

• Defining a Function:
  To define a function in Python, use the def keyword followed by the function name and parentheses. For example:

  def greet():
      print("Hello, World!")

• Function Name:
  The function name should follow Python's naming conventions (letters, digits, and underscores; should not start with a digit).
• Parameters:
  Functions can accept parameters (inputs) enclosed in the parentheses. Parameters are optional and allow you to pass values to the function. For example:

  def greet_person(name):
      print(f"Hello, {name}!")
  

• Calling a Function:
  To execute a function, we call it by its name followed by parentheses. Example of calling the greet() function defined earlier:

  greet()
  

• Arguments:
  When we call a function, we provide arguments for the parameters defined in the function. These are the actual values we want the function to work with. For example, calling greet_person("Alice") with "Alice" as the argument for the name parameter.
  Without parameters:

  greet()
  

  With parameters:

  greet_person("Alice")
  

  We can also return the values as:

  result = add(5, 3)
  print("5 + 3 =", result)
  

  Default Parameters:
  We can set default values for parameters in function definitions. These values are used if no argument is provided. Example:

  def greet_with_default(name="World"):
      print(f"Hello, {name}!")
  

  Arbitrary Arguments:
  We can use *args to pass a variable number of non-keyword arguments to a function. Example:

  def sum_numbers(*args):
      total = 0
      for num in args:
          total += num
      return total
  

LAMBDA Functions or Anonymous Functions
Lambda functions are not defined as other functions using the def keyword, rather they are created using the lambda keyword. They have no function name, and can take any number of arguments. But they can return just one value in the form of an expression. They are a one-line version of a function and hence cannot contain multiple expressions. They also cannot access the global variables.
For your understanding, kindly go through the video and also the code example below...

# functions

# user-defined functions

# '''function definition'''
# def function_name():
#     pass
# '''function call'''
# function_name()
# print("this is a statement")

# parameter - variables to be used in the function
# def newFunc(x, y):
#     return x - y
# a = 10
# b = 5
# callFunc = newFunc(a, b)
# print("the value is", callFunc)

# def func():
#     for i in range(4):
#         print("Hello world")
# func()
'''
def newFuncs(x, y):
    return x * y

# newFuncs(5)  will give error because the argument and the parameter do not match
printValue = newFuncs(5, 10)
print(printValue)
'''
# default argument
# def display(name, course="BCA"):
#     print("Name:", name)
#     print("Course:", course)
# my_name = "Rajjit"
# display(my_name)

# lambda function
'''
syntax: lambda argument: expression
'''
# def sum(x, y):
#     print(x + y)
# sum(12, 8)

# sum2 = lambda x, y : x + y
# print(sum2(12, 12))

# Q. write a program to check whether two number are equal or not

def check(a, b):
    if(a == b):
        print("a and b are equal")
    elif (a > b):
        print("a is greater than b")
    else:
        print("a is lesser than b")

check(5, 12)