code: public CsvWriter<T> append(T value) throws IOException {
          try {
              mapper.mapTo(value, appendable, mappingContext);
          } catch(Exception e) {
              ErrorHelper.rethrow(e);
          }
          return this;
      }
docs: write the specified value to the underlying appendable.
  @param value the value to write
  @return the current writer
  @throws IOException If an I/O error occurs