parse xml file to csv.
each data entry is in different tag
the fields within the tags are predefined, however, there might be repetition of fields.
for example, if the data is on books, there might be more than one author, than the field author would appear more than once in the xml entry for that book. the actual number of repetition foe each data entry is in the file as well, but we can limit it to 10.
for each data entry the application will create a row in csv file, where each field (tag) would be a column. for the repeated attributes, new column will be created with the field name + index (author 1, author 2,,,)
the application must work efficiently, as the file size is ~3GB.