code: public double getDoubleValue() throws DOMException {
          if (value_ instanceof LexicalUnit) {
              final LexicalUnit lu = (LexicalUnit) value_;
              return lu.getDoubleValue();
          }
          throw new DOMExceptionImpl(
              DOMException.INVALID_ACCESS_ERR,
              DOMExceptionImpl.FLOAT_ERROR);
  
          // We need to attempt a conversion
          // return 0;
      }
docs: @return the double value.
  
  @throws DOMException in case of error