Different Set Operations

A = {1,2,3,4,5,6,7,8};
B = {5,10,15,20,25,30,35,40};
   
print("Union of A and B is",A | B)

print("\nIntersection of A and B is",A & B)

print("\nDifference of A and B is",A - B)

print("\nSymmetric difference of A and B is",A ^ B)

Use pass for an empty block

#Credits to NPTEL MOOC, Programming, Data Structures & Algorithms in 
#Python by Madhavan Mukund, Chennai Mathematical Institute 

while(True):  
  try:
    userdata = input("Enter a number: ")
    usernum = int(userdata)
  except ValueError:
    print("Not a number. Try again")
  except NameError:
    pass
  else:
    break