How to read a group of datasets as files in a folder?

Question

I am working with sunpy's class sunpy.map.Map(), which operates '.fits' files. Usually, it collects those files directly through directories:

import sunpy.map

map_seq = sunpy.map.Map('C:/Usr/sunpy/data')

However, I am looking for a way of using this .Map() function with already opened '.fits' files on the code. I have a list of 3 '.fits' files and have tried:

map_seq = sunpy.map.Map(['fits1.fits','fits2.fits','fits3.fits'])

But it returns: IndexError: pop index out of range. Is there a way of doing that?