code: public Double getDouble(String key, Double defaultValue) throws SyntaxException
      {
          String value = getSimple(key);
          if (value == null)
          {
              return defaultValue;
          }
          else
          {
              try
              {
                  return Double.valueOf(value);
              }
              catch (NumberFormatException e)
              {
                  throw new SyntaxException(String.format("Invalid double value %s for '%s'", value, key));
              }
          }
      }
docs: Return a property value, typed as a Double