docs: def set_basefilemtime(self):
          """Set attributes mtimestamp and mtimefs. If the global list
          ORIGINEXTENSIONS include any items, try and look for files (in
          the directory where self.filename is sitting) with the same base
          name as the loaded file, but with an extension specified in
          ORIGINEXTENSIONS.
  
          mtimestamp is a timestamp and mtimefs is the file (name) with
          that timestamp.
  
          ORIGINEXTENSIONS is empty on delivery. Which means that the
          attributes discussed will be based on the file that was loaded,
          (unless ORIGINEXTENSIONS is populated before this call).
  
          This is supposed to be a convenience in cases the data file
          loaded is some sort of "exported" file format, and the original
          file creation time is of interest.
  
          .. note::
             If the provided functions in this module is used to get a
             pack, this method does not have to be called. It is called by
             those functions.
          """
  
          dirpath = os.path.split(self.filename)[0]
          name = os.path.basename(self.fs).split('.')[0]
          for ext in ORIGINEXTENSIONS:  # This should be some user configuration.
              res = glob.glob(dirpath + '/' + name + '.' + ext)
              if res:             # Assume first match is valid.
                  # If some shell patterns will be used later
                  self.mtimefs = os.path.normpath(res[0])
                  # Time stamp string:
                  self.mtimestamp = time.ctime(os.path.getmtime(self.mtimefs))
                  break
          else:
              self.mtimefs = self.filename
              self.mtimestamp = time.ctime(os.path.getmtime(self.mtimefs))