code: def resolver_class_for_source(self, source):
      if source.parsed_uri.scheme == "dvcfile":
          return DvcFileResolver
      if source.parsed_uri.scheme == "dvcstage":
          return DvcStageResolver
      return None
  
imports: import copy
  import logging
  import os
  from guild import config
  from guild import guildfile
  from guild import model
  from guild import plugin
  from guild import resolver
  from guild import resourcedef
  from guild import run_manifest
  from guild import util
  from .None import dvc_util
label_desc: Use image node_id 4 for calling the DvcPlugin obj's underlying member method code with example usage: obj.resolver_class_for_source(source) and returns: None, DvcFileResolver, DvcStageResolver