Fix Python – Pandas: Looking up the list of sheets in an excel file

The new version of Pandas uses the following interface to load Excel files:
read_excel(‘path_to_file.xls’, ‘Sheet1’, index_col=None, na_values=[‘NA’])

but what if I don’t know the sheets that are available?
For example, I am working with excel files that the following sheets

Data 1, Data 2 …, Data N, foo, bar

but I don’t know N a priori.
Is ….