          elif isinstance(k, tuple):
              msgid = k[0]
              cnt = k[1]
              maxcnts[msgid] = max(cnt, maxcnts.get(msgid, 0))
              pdict.setdefault(msgid, {})[cnt] = v
          else:
              raise TypeError(k)
      for k, v in pdict.items():
          catalog[k] = [v.get(i, '') for i in range(maxcnts[msgid] + 1)]
  
 
</s> remove             raise TypeError(k)
 </s> add             raise TypeError(key) </s> remove         if isinstance(k, six.string_types):
            catalog[k] = v
        elif isinstance(k, tuple):
            msgid = k[0]
            cnt = k[1]
 </s> add         if isinstance(key, six.string_types):
            catalog[key] = value
        elif isinstance(key, tuple):
            msgid = key[0]
            cnt = key[1] </s> remove     for k, v in t.items():
        if k == '':
 </s> add     trans_fallback_cat = trans._fallback._catalog if trans._fallback else {}
    for key, value in itertools.chain(six.iteritems(trans_cat), six.iteritems(trans_fallback_cat)):
        if key == '' or key in catalog: </s> remove     t = {}
 </s> add  </s> remove     en_selected = locale.startswith('en')
    en_catalog_missing = True
 </s> add 
            pdict.setdefault(msgid, {})[cnt] = value
          elif isinstance(k, tuple):
              msgid = k[0]
              cnt = k[1]
              maxcnts[msgid] = max(cnt, maxcnts.get(msgid, 0))
            pdict.setdefault(msgid, {})[cnt] = value
          else:
              raise TypeError(k)
      for k, v in pdict.items():
          catalog[k] = [v.get(i, '') for i in range(maxcnts[msgid] + 1)]
  
keep keep keep keep replace keep keep keep keep keep
 Reused the DjangoTranslation class for the javascript_catalog view

Thanks Tim Graham and Cristiano Coelho for the reviews.
Refs #26328, #26319. 
django/views/i18n.py