docs: def fix_paths(self, paths):
          """
          Fix the filenames in the iterable paths
  
          Returns:
              old2new: Mapping old_path --> new_path
          """
          old2new, fixed_exts = {}, []
  
          for path in list_strings(paths):
              newpath, ext = self._fix_path(path)
  
              if newpath is not None:
                  #if ext not in fixed_exts:
                  #    if ext == "1WF": continue
                  #    raise ValueError("Unknown extension %s" % ext)
                  #print(ext, path, fixed_exts)
                  #if ext != '1WF':
                  #    assert ext not in fixed_exts
                  if ext not in fixed_exts:
                      if ext == "1WF": continue
                      raise ValueError("Unknown extension %s" % ext)
                  fixed_exts.append(ext)
                  old2new[path] = newpath
  
          return old2new