(i) The value returned by a function may be used as an argument for another function in a nested manner.
(ii) This is called composition, For example, if we wish to take a numeric value or an expression as a input from the user, we take the input string from the user using the function input() and apply eval() function to evaluate its value.

Code:
n=int(input("Enter the year"))
if(y%4==0):
         print ("Leap Year")
else:
         print ("Not a Leap Year")
Output:
Enter the year      2012
Leap Year

S.No ceil ( ) floor ( ) (i) Returns the smallest integer greater than or equal to x. Returns the largest integer less than or equal to x. (ii) Syntax: math. ceil (x) Syntax: math.floor (x)

If we modify the global variable, we can see the change on the global variable outside the function also.
Example:
x=0                                                                                     # global variable
def add():
       global x
        x=x+5                                                                         # increment by 5
     print ("Inside add() function x value is:",x)
  add()
  print ("In main x value is:", x)
Output:
Inside add() function x value is: 5
In main x value is: 5                                                          #value of x changed outside the function

Rules of global Keyword: The basic rules for global keyword in Python are:
(i) When we define a variable outside a function, it's global by default. you don't have to use global keyword.
(ii) We use global keyword to modify the value of the global variable inside a function.
(iii) Use of global keyword outside a function has no effect.