* lisp/progmodes/python.el (python--treesit-settings): Add docstring.
(python--imenu-treesit-create-index-1): Rewrite with
treesit-induce-sparse-tree.
(python-imenu-treesit-create-index): Move main body to
python--imenu-treesit-create-index-1.
(python-imenu-treesit-create-flat-index): Fix typo.
(python-mode): Enable treesit-imenu. Also fix indentation for
which-func code.