code: def add_implicit_resolver(cls, tag, regexp, first):
      if not "yaml_implicit_resolvers" in cls.__dict__:
          implicit_resolvers = {}
          for key in cls.yaml_implicit_resolvers:
              implicit_resolvers[key] = cls.yaml_implicit_resolvers[
                  key
              ][:]
          cls.yaml_implicit_resolvers = implicit_resolvers
      if first is None:
          first = [None]
      for ch in first:
          cls.yaml_implicit_resolvers.setdefault(ch, []).append(
              (tag, regexp)
          )
  
file_path: catboost/contrib/python/PyYAML/py3/yaml/resolver.py
imports: from .error import *
  from .nodes import *
  import re
label_desc: Use image node_id 2 for calling the BaseResolver obj's underlying member method code with example usage: obj.add_implicit_resolver(cls, tag, regexp, first) without return types