class_docstr: Higher order selection rule using git ignored files.
  
  This is a 'select everything except ignored' rule and can be used
  in place of a select '*' select rule - with the exception that git
  ignored files are not selected.
code: def test(self, _src_root, relpath):
      # This is a 'select everything except ignored' rule so we
      # return `True` to select anything that isn't in our list of
      # ignored. This could alternatively be a `False` for anything
      # in ignored, but this would require an explicit select '*'
      # rule to precede it.
      if relpath not in self.ignored:
          return True, None
      return None, None
  
imports: import collections
  import logging
  import re
  import os
  import subprocess
  from guild import config
  from guild import file_util
  from guild import util
  from guild.file_util import FileSelectRule
label_desc: Use image node_id 3 for calling the _GitignoreSelectRule obj's underlying member method code with example usage: obj.test(_src_root, relpath) and returns: None,  None, True,  None