FIX: coerce None to 0 for refining
FIX: coerce None to 0 for refining


PhonologicalCorpusTools/PolyglotDB,PhonologicalCorpusTools/PyAnnotationGraph,MontrealCorpusTools/PolyglotDB,PhonologicalCorpusTools/PolyglotDB,MontrealCorpusTools/PolyglotDB,PhonologicalCorpusTools/PyAnnotationGraph