old_contents: # -*- coding: utf-8 -*-
  
  from infcommon.factory import Factory
  from infcommon.yaml_reader.yaml_reader import YamlReader
  
  
  def yaml_reader(path=None):
      return Factory.instance('yaml_reader', lambda: YamlReader(path))
  
new_contents: # -*- coding: utf-8 -*-
  
  import os
  
  from infcommon.factory import Factory
  from infcommon.yaml_reader.yaml_reader import YamlReader
  
  
  DEFAULT_PATH_ENVIRONMENT_VARIABLE_NAME = 'CONF_FILE'
  
  
  def yaml_reader(path=None):
      path = path or os.environ[DEFAULT_PATH_ENVIRONMENT_VARIABLE_NAME]
      return Factory.instance('yaml_reader',
                              lambda: YamlReader(path))
  
subject: Use environment variable with deafult path when no path given