code: def _val(var, is_percent=False):
      
      try:
          if is_percent:
              var = float(int(var.strip('%')) / 100.0)
          else:
              var = int(var)
      except ValueError:
          raise ValueError('invalid watermark parameter: ' + var)
      return var
docs: Tries to determine the appropriate value of a particular variable that is
      passed in.  If the value is supposed to be a percentage, a whole integer
      will be sought after and then turned into a floating point number between
      0 and 1.  If the value is supposed to be an integer, the variable is cast
      into an integer.