http://www.elasticsearch.org/guide/reference/query-dsl/fuzzy-query.html
        A fuzzy based query that uses similarity based on Levenshtein (edit distance) algorithm.

def fuzzy(cls, field, value, boost=None, min_similarity=None, prefix_length=None):
        '''
        http://www.elasticsearch.org/guide/reference/query-dsl/fuzzy-query.html
        A fuzzy based query that uses similarity based on Levenshtein (edit distance) algorithm.
        '''
        instance = cls(fuzzy={field: {'value': value}})
        if boost is not None:
            instance['fuzzy'][field]['boost'] = boost
        if min_similarity is not None:
            instance['fuzzy'][field]['min_similarity'] = min_similarity
        if prefix_length is not None:
            instance['fuzzy'][field]['prefix_length'] = prefix_length
        return instance