code: public String readLineSkippingComments(boolean trim) throws IOException {
          for (;;) {
              String line = readLine();
              if (line == null) {
                  return line;
              }
              // Skip over white space
              int pos = PatternProps.skipWhiteSpace(line, 0);
              // Ignore blank lines and comment lines
              if (pos == line.length() || line.charAt(pos) == '#') {
                  continue;
              }
              // Process line
              if (trim) line = line.substring(pos);
              return line;
          }
      }
docs: Read a line, ignoring blank lines and lines that start with
  '#'.
  @param trim if true then trim leading Pattern_White_Space.