code: public static int copy(Reader reader, Writer writer, boolean closeWriter) {
          if (closeWriter) {
              return write(reader).ensureCloseSink().to(writer);
          } else {
              return write(reader).to(writer);
          }
      }
docs: Copy from a `Reader` into a `Writer`.
  
  @param reader
  A reader - the source
  @param writer
  a writer - the target
  @param closeWriter
  indicate if it shall close the writer after operation
  @return the number of chars copied