code: def _marker_files(self, tar, members):
          
          marker_files = {}
  
          self.log.debug(
              "Searching for marker files in '%s' archive..." % tar.name)
  
          for member in members:
              if '.wh.' in member.name:
                  self.log.debug("Found '%s' marker file" % member.name)
                  marker_files[member] = tar.extractfile(member)
  
          self.log.debug("Done, found %s files" % len(marker_files))
  
          return marker_files
docs: Searches for marker files in the specified archive.
  
          Docker marker files are files taht have the .wh. prefix in the name.
          These files mark the corresponding file to be removed (hidden) when
          we start a container from the image.