docs: def guess_extension(amimetype, normalize=False):
      """
      Tries to guess extension for a mimetype.
  
      @param amimetype: name of a mimetype
      @time amimetype: string
      @return: the extension
      @rtype: string
      """
      ext = _mimes.guess_extension(amimetype)
      if ext and normalize:
          # Normalize some common magic mis-interpreation
          ext = {'.asc': '.txt', '.obj': '.bin'}.get(ext, ext)
          from invenio.legacy.bibdocfile.api_normalizer import normalize_format
          return normalize_format(ext)
      return ext