[Zope] tutorial script error

[Raymond Norton]

I am following the tutorial. When I attempt to add this script I get a
syntax error on line 1. It doesn't like the quotes.

Can anyone give me advice on this?

## Script (Python) "calculateCompoundInterest"
      ##parameters=principal, interest_rate, periods, years
      ##
      """
      Calculate compounding interest.
      """
      i = interest_rate / periods
      n = periods * years
      return ((1 + i) ** n) * principal

Raymond