Great video. I can call `DocxDocumentParser` by `Document.new( 'some_path', 'DocxDocumentParser').parse` ?
Line 4 in Document initialize, does `parser` needs `constantize` ?
Not tried this myself but I think you need to remove the quotes DocxDocumentParser so you don't pass in a string. You should pass in a class so that the initialize method on Document can call #new on it.