code: private boolean parseBoolean(String s) {
          if ( "1".equals(s) ) {
              return true;
          } else if ( "0".equals(s) ) {
              return false;
          } else {
              throw new IllegalArgumentException("Expected 1 or 0 for boolean value, was " + s);
          }
      }
docs: Attempts to parse the string given as a boolean and return its value.
  Throws an exception if the value is anything other than 0 or 1.