title: Putting together conditionals, input casting, and math
body: <p>I wrote the code below with a single parameter <code>operator</code>. This parameter can only contain <code>*</code> or <code>/</code> operator as argument. My question is: Is it possible to define this argument, so that the user knows he/she can only put <code>*</code> or <code>/</code> operator as argument? (The default operator is <code>*</code>)</p>
  
  <pre><code>def mult_or_divid(operator = "*"):
      integer1 = int(input("enter a whole number: "))
      integer2 = int(input("enter a whole number: "))
      if operator == "*":
          return(integer1 * integer2)
      elif operator == "/":
          return(integer1 / integer2)
      else:
          return("Invalid Operator")
  
  print(mult_or_divid("/"))
  </code></pre>