def add(num1,num2):
    result=num1+num2
    return result
def sub(num1,num2):
    result=num1-num2
    return result
def mul(num1,num2):
    result=num1*num2
    return result
def div(num1,num2):
    result=num1/num2
    return result
#python file(.py) is knwon as MODULE
#collection of modules is known as PACKAGE
