code: private String extractLanguage(String columnHeading) throws ParseException {
      int start = columnHeading.indexOf('(');
      int end = columnHeading.indexOf(')');
  
      if (start == -1 || end == -1 || start >= end) {
        throwWrongHeaderException();
      }
      return columnHeading.substring(start + 1, end);
    }
docs: Extracts the language of the "master language value" and "value"
  column heading in the first line of the trema CSV file.
  @param columnHeading the column heading. The expected format is:
  <code>master (&lt;lang&gt;)</code> or <code>value (&lt;lang&gt;)</code>.
  @return the extracted language
  @throws ParseException if any parse errors occur