code: private void checkLineBeginsWith(String line, String expect, int lineCount) throws CDKException {
          if (line == null) {
              throw new CDKException("RGFile invalid, empty/null line at #" + lineCount);
          }
          if (!line.startsWith(expect)) {
              throw new CDKException("RGFile invalid, line #" + lineCount + " should start with:" + expect + ".");
          }
      }
docs: Checks that a given line starts as expected, according to RGFile format.
  @param line
  @param expect
  @param lineCount
  @throws CDKException