class_docstr: An extension of CompletionFinder which dynamically completes class-trait based options
  
  This finder adds a few functionalities:
  
  1. When completing options, it will add ``--Class.`` to the list of completions, for each
  class in `Application.classes` that could complete the current option.
  2. If it detects that we are currently trying to complete an option related to ``--Class.``,
  it will add the corresponding config traits of Class to the `ArgumentParser` instance,
  so that the traits' completers can be used.
  3. If there are any subcommands, they are added as completions for the first word
  
  Note that we are avoiding adding all config traits of all classes to the `ArgumentParser`,
  which would be easier but would add more runtime overhead and would also make completions
  appear more spammy.
  
  These changes do require using the internals of `argcomplete.CompletionFinder`.
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docstr: Overridden to add --Class. completions when appropriate
docstr_tok: ["Overridden","to","add","--","Class",".","completions","when","appropriate"]
code: def _get_option_completions(
      self, parser: argparse.ArgumentParser, cword_prefix: str
  ) -> t.List[str]:
      """Overridden to add --Class. completions when appropriate"""
      completions: t.List[str]
      completions = super()._get_option_completions(
          parser, cword_prefix
      )  # type:ignore[no-untyped-call]
      if cword_prefix.endswith("."):
          return completions
  
      matched_completions = self.match_class_completions(cword_prefix)
      if len(matched_completions) > 1:
          completions.extend(opt for cls, opt in matched_completions)
      # If there is exactly one match, we would expect it to have already
      # been handled by the options dynamically added in _get_completions().
      # However, maybe there's an edge cases missed here, for example if the
      # matched class has no configurable traits.
      return completions
  
file_path: catboost/contrib/python/traitlets/py3/traitlets/config/argcomplete_config.py
imports: import argparse
  import os
  import typing
label_desc: Use image node_id 4 for calling the ExtendedCompletionFinder obj's underlying member method code with example usage: obj._get_option_completions(parser, cword_prefix) and returns: completions, completions