ExcelReaders: suggestion about adding a way to close an .xlsx file after opening it with “openxl”

[ale111111]

Hello,

I am using Julia 0.6.4 and the ExcelReaders package to read several sheets from a very large .xlsx file.
Thus, instead of repeating foo_n = readxlsheet("data.xlsx", "sheetname_n") for n times, it seemed to me to be more convenient and faster to use:

main_file = openxl("data.xlsx")
foo_1 = readxlsheet(main_file, "sheetname_1")
foo_2 = readxlsheet(main_file, "sheetname_2")
...

Which, if I got it right, keeps the whole large file "data.xlsx" in memory, so to permit a faster access whenever e.g. a new sheet needs to be read.
However, how about adding a feature to close such a large file (once not needed anymore in the program)? It could be something like: closexl("data.xlsx").
I presume that by freeing up some memory, the latter could be used to run faster a very long script for instance.

Thank you in advance!