  
  class Lemmatizer(object):
      @classmethod
      def load(cls, path, index=None, exc=None, rules=None, lookup=None):
          return cls(index or {}, exc or {}, rules or {}, lookup or {})
  
      def __init__(self, index=None, exceptions=None, rules=None, lookup=None):
          self.index = index if index is not None else {}
          self.exc = exceptions if exceptions is not None else {}
          self.rules = rules if rules is not None else {}
 
</s> remove         self.index = index if index is not None else {}
        self.exc = exceptions if exceptions is not None else {}
        self.rules = rules if rules is not None else {}
 </s> add         self.index = index
        self.exc = exceptions
        self.rules = rules
        return cls(index, exc, rules, lookup)
  
  class Lemmatizer(object):
      @classmethod
      def load(cls, path, index=None, exc=None, rules=None, lookup=None):
        return cls(index, exc, rules, lookup)
  
      def __init__(self, index=None, exceptions=None, rules=None, lookup=None):
          self.index = index if index is not None else {}
          self.exc = exceptions if exceptions is not None else {}
          self.rules = rules if rules is not None else {}
keep keep keep keep replace keep keep keep keep keep
 If no rules are set, lemmatize by lookup 
spacy/lemmatizer.py