code: def _operation_flag_default():
      """Returns the default flag value for an operation source.
  
      This value is always None to ensure that Guild applies the default
      run resolution algorithm at run time.
      """
      return None
  
file_path: guildai/guild/plugins/resource_flags.py
imports: import logging
  from guild import guildfile
  from guild import op_dep
  from guild import plugin
label_desc: Use image node_id 9 for calling a global function with example usage: _operation_flag_default() and returns: None