Prolog printer

[kovvalsky]

For me the prolog printer is not working while other printers are fine.
When I run the parser programmatically I find that Tree.prolog() inserts numbers instead of tokens in the f-string.

ccg({0},
 rp(s:dcl, 
  ba(s:dcl, 
   t(np, 'This', '{32766.lemma}', '{32766.pos}', '{32766.chunk}', '{32766.entity}'),
   fa((s:dcl\np), 
    t(((s:dcl\np)/(s:adj\np)), 'is', '{32767.lemma}', '{32767.pos}', '{32767.chunk}', '{32767.entity}'),
    t((s:adj\np), 'second', '{32768.lemma}', '{32768.pos}', '{32768.chunk}', '{32768.entity}'))),
  t(period, '.', '{32769.lemma}', '{32769.pos}', '{32769.chunk}', '{32769.entity}'))).

The following shows that other formats work while prolog doesn't.

$ echo "Prolog printer inserts numbers" | python3 -m depccg en "$@" -f deriv --silent 

ID=1, log probability=-0.32995718717575073
  N/N       N     (S[dcl]\NP)/NP     N
 Prolog  printer     inserts      numbers
----------------->
        N
-----------------<un>
       NP
                                 ---------<un>
                                    NP
                 ------------------------->
                         S[dcl]\NP
------------------------------------------<
                  S[dcl]

$ echo "Prolog printer inserts numbers" | python3 -m depccg en "$@" -f prolog --silent 

Traceback (most recent call last):
  File "/usr/lib/python3.6/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/local/lib/python3.6/dist-packages/depccg-1.0.7-py3.6-linux-x86_64.egg/depccg/__main__.py", line 259, in <module>
    args.func(args)
  File "/usr/local/lib/python3.6/dist-packages/depccg-1.0.7-py3.6-linux-x86_64.egg/depccg/__main__.py", line 125, in main
    semantic_templates=semantic_templates)
  File "/usr/local/lib/python3.6/dist-packages/depccg-1.0.7-py3.6-linux-x86_64.egg/depccg/printer.py", line 299, in print_
    print(to_prolog_en(nbest_trees, tagged_doc), end='', file=file)
  File "/usr/local/lib/python3.6/dist-packages/depccg-1.0.7-py3.6-linux-x86_64.egg/depccg/printer.py", line 46, in to_prolog_en
    print(t.prolog().format(i, *tokens), file=output)
AttributeError: 'int' object has no attribute 'lemma'