This is uTidylib, the Python wrapper for the HTML cleaning library named TidyLib. It supports both original Tidy <https://tidy.sf.net> and new HTML5 enabled Tidy <https://www.html-tidy.org/>.
The package is available on PyPI <https://pypi.org/project/uTidylib/>.
Once installed, there are two ways to get help. The simplest is:
$ python
>>> import tidy
>>> help(tidy)
. . .
Then, of course, there's the API documentation, which is available at <https://utidylib.readthedocs.io/en/latest/>.
>>> import tidy
>>> print(
... tidy.parseString(
... "<Html>Hello Tidy!",
... output_xhtml=1,
... add_xml_decl=1,
... indent=1,
... tidy_mark=0,
... doctype="transitional",
... )
... )
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="https://www.w3.org/1999/xhtml">
<head>
<title></title>
</head>
<body>
Hello Tidy!
</body>
</html>
Good luck!