"""File:     arithmetic.py
   Purpose:  Execute a basic arithmetic operation

   Run:      python arithmetic.py

   Input:    value1 
             operator 
             value2
             (operator can be +, -, *, or /)
   Output:   The result of value1 operator value2
"""
def execute_op(val1, op, val2):
   if op == '+':
      return val1 + val2
   elif op == '-':
      return val1 - val2
   elif op == '*':
      return val1*val2
   elif op == '/':
      return val1/val2
   else:
      return None

#----------------------------------------------------------------------
# Program starts executing here
val1 = float(raw_input("Enter a number\n"))
op = raw_input("Enter an operation (+, -, *, /)\n")
val2 = float(raw_input("Enter a number\n"))
result = execute_op(val1, op, val2)
if result == None:
   print op, "isn't a valid operation"
else:
   print val1, op, val2, "=", result