def register_writer(klass):
if not callable(klass):<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>engine_name = klass.engine<EOL>_writers[engine_name] = klass<EOL>
Add engine to the excel writer registry.io.excel.

You must use this method to integrate with ``to_excel``.

Parameters
----------
klass : ExcelWriter