tyler has defined a ``_repr_html_``
to automatically render itself. Otherwise call Styler.to_html to get
the generated HTML.
CSS classes are attached to the generated HTML
* Index and Column names include ``index_name`` and ``level``
where `k` is its level in a MultiIndex
* Index label cells include
* ``row_heading``
* ``row`` where `n` is the numeric position of the row
* ``level`` where `k` is the level in a MultiIndex
* Column label cells include
* ``col_heading``
* ``col`` where `n` is the numeric position of the column
* ``level`` where `k` is the level in a MultiIndex
* Blank cells include ``blank``
* Data cells include ``data``
* Trimmed cells include ``col_trim`` or ``row_trim``.
Any, or all, or these classes can be renamed by using the ``css_class_names``
argument in ``Styler.set_table_classes``, giving a value such as
*{"row": "MY_ROW_CLASS", "col_trim": "", "row_trim": ""}*.
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