Columns with `.` in their name get ignored

[LowNightSnack]

It seems columns with . in their names get ignored. Example:

xlsx([{sheet: "test", columns: [{label: "Ex. Rate", value: "Ex. Rate"}], content: [{"Ex. Rate": 1}, {"Ex. Rate": 1}, {"Ex. Rate": 1}, {"Ex. Rate": 1}], {fileName: "Test"})

[LowNightSnack]

If this is not how should the function should be used, please add this in the docs. If there is something I can help with, I'll contribute too.