private void flushLeft() throws IOException {
    appendNewlineIfNecessary(leftBuf, leftColumn);

    while (leftBuf.length() != 0) {
      rightColumn.write('\n');
      outputFullLines();
    }
  }
Flushes the left column buffer, printing it and clearing the buffer. If the buffer is already
empty, this does nothing.
android/android_framework/dex-maker/src/main/java/com/android/dx/util/TwoColumnOutput.java