String separator = System.getProperty("line.separator");
    sink.writeLines(lines);

    assertContainsExpectedLines(separator);
  }

  public void testWriteLines_specificSeparator() throws IOException {
    String separator = "\r\n";
    sink.writeLines(lines, separator);

    assertContainsExpectedLines(separator);
  }

    String separator = System.getProperty("line.separator");
    sink.writeLines(lines);

    assertContainsExpectedLines(separator);
  }

  public void testWriteLines_specificSeparator() throws IOException {
    String separator = "\r\n";
    sink.writeLines(lines, separator);

    assertContainsExpectedLines(separator);
  }

  }

  public void testWriteLines_withSpecificSeparator() throws IOException {
    sink.writeLines(ImmutableList.of("foo", "bar", "baz"), "\n");
    assertThat(sink.getString()).isEqualTo("foo\nbar\nbaz\n");
  }

  public void testWriteLines_withDefaultSeparator() throws IOException {
    sink.writeLines(ImmutableList.of("foo", "bar", "baz"));
    String separator = System.getProperty("line.separator");

  }

  public void testWriteLines_withSpecificSeparator() throws IOException {
    sink.writeLines(ImmutableList.of("foo", "bar", "baz"), "\n");
    assertThat(sink.getString()).isEqualTo("foo\nbar\nbaz\n");
  }

  public void testWriteLines_withDefaultSeparator() throws IOException {
    sink.writeLines(ImmutableList.of("foo", "bar", "baz"));
    String separator = System.getProperty("line.separator");

        today = date.today().isoformat()
        lines[i] = f"## {version} ({today})\n"
        print(f"Added date: {version} ({today})")

        with open(RELEASE_NOTES_FILE, "w") as f:
            f.writelines(lines)
        sys.exit(0)

    print("No release header found")
    sys.exit(1)


if __name__ == "__main__":

                    permalinks.add(slug)

                    line = f"{hashes} {title} {{ #{slug} }}\n"

        updated_lines.append(line)

    with path.open("w", encoding="utf-8") as f:
        f.writelines(updated_lines)


@app.command()
def add_permalinks_pages(pages: list[Path], update_existing: bool = False) -> None:
    """
    Add or update header permalinks in specific pages of En docs.
    """