def __init__(self, parents=lambda term: [], children=lambda term: [], value=lambda term: None):
self.parents  = parents<EOL>self.children = children<EOL>self.value    = value<EOL>
A classifier uses a rule-based approach to enrich the taxonomy, for example:
            c = Classifier(parents=lambda term: term.endswith("ness") and ["quality"] or [])
            taxonomy.classifiers.append(c)
            This tags any word ending in -ness as "quality".
            This is much shorter than manually adding "roughness", "sharpness", ...
            Other examples of useful classifiers: calling en.wordnet.Synset.hyponyms() or en.number().