Indexing the output of XLSX.readtable() in the "01. Data.ipynb" results in a MethodError.
According to the Docs of XLSX, the output has been converted to a class instead of a tuple.
Hence, the indexing in the following cells does not work.
As a fix, I would store it directly inside the DataFrame.

However, since I have only installed Julia for one hour, I do not feel comfortable to rewrite the introduction :)