(i) Python stops calling recursive function after 1000 calls by default. 
(ii) So, it also allows you to change the limit using sys.setrecursionlimit (limit_value).
Example:
import sys
sys.setrecursionlimit(3000)
def fact(n):
         if n == 0:
         return 1
         else:
         return n * fact(n-1)
print(fact (2000))

(i)  A recursive function calls itself.
(ii) The condition that is applied in any recursive function is known as base condition.
(iii)  A base condition is must in every recursive function otherwise it will continue to execute like an infinite loop.

A variable with global scope can be used anywhere in the program. It can be created by defining a variable outside the scope of any function.

When defining functions there are multiple things that need to be noted;
(i) Function blocks begin with the keyword "def" followed by function name and parenthesis ().
(ii) If any input parameters are present should be placed within these parentheses when you define a function.
(iii) The code block always comes after colon(:) and is indented.
(iv) The statement "return [expression]" exits a function, optionally passing back an expression to the caller. A "return" with no arguments is the same as return None.

(i) Recursive function is called by some external code.
(ii) If the base condition is met then the program gives meaningful output and exits.
(iii) Otherwise, function does some required processing and then calls itself to continue recursion.

(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.

(i) When a function calls itself is known as recursion.
(ii) Recursion works like loop but sometimes it makes more sense to use recursion than loop.
(iii) You can convert any loop to recursion. A recursive function calls itself.
(iv) Imagine a process would iterate indefinitely if not stopped by some condition is known as infinite iteration.
(v) The condition that is applied in any recursive function is known as base condition.
(vi) A base condition is must in every recursive function otherwise it will continue to execute like an infinite loop.
Overview of how recursive function works: 
(i) Recursive function is called by some external code.
(ii) If the base condition is met then the program gives meaningful output and exits.
(iii) Otherwise, function does some required processing and then calls itself to continue recursion.
Here is an exanmple of recursive function used to calculate factorial.
Example:
def fact(n):
if n == 0:
             return 1
else:
             return n * fact (n-1)
print (fact (0))
print (fact (5))
Output:
120

Program:
def lcm(x, y):
if x>y:
       greater = x
else:
       greater = y
while (True):
        if ((greater % x == 0) and (greater % y ==0))
        lcm = greater
        break
        greater + = 1
        return lcm
a = int (input ("Enter the first number:"))
b = int (input ("Enter the second number: "))
print ("The L.C.M of", a, "and", b, "is", lcm (a, b))
                      [OR]
Method II: (without using functions)
a = int (input ("Enter the first number:"))
b = int (input ("Enter the second number:"))
if a>b:
       mini a
else:
       min 1 = b
       while (1):
if (min 1% a 0 and mini 1% b=0):
print ("LCM is:", mini)
break
mini = min 1+1
Output:
Enter the first number: 15
Enter the second number: 20
LCM is: 60