class_docstr: Manage the parallelism and checker instances for each plugin and file.
  
  This class will be responsible for the following:
  
  - Determining the parallelism of Flake8, e.g.:
  
    * Do we use :mod:`multiprocessing` or is it unavailable?
  
    * Do we automatically decide on the number of jobs to use or did the
      user provide that?
  
  - Falling back to a serial way of processing files if we run into an
    OSError related to :mod:`multiprocessing`
  
  - Organizing the results of each checker so we can group the output
    together and make our output deterministic.
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docstr: Initialize our Manager instance.
code: def __init__(
      self,
      style_guide: StyleGuideManager,
      plugins: Checkers,
      argv: Sequence[str],
  ) -> None:
      """Initialize our Manager instance."""
      self.style_guide = style_guide
      self.options = style_guide.options
      self.plugins = plugins
      self.jobs = self._job_count()
      self.statistics = {
          "files": 0,
          "logical lines": 0,
          "physical lines": 0,
          "tokens": 0,
      }
      self.exclude = (
          *self.options.exclude,
          *self.options.extend_exclude,
      )
      self.argv = argv
      self.results: list[tuple[str, Results, dict[str, int]]] = []
  
imports: from __future__ import annotations
  import argparse
  import contextlib
  import errno
  import logging
  import multiprocessing.pool
  import operator
  import signal
  import tokenize
  from typing import Any
  from typing import Generator
  from typing import List
  from typing import Optional
  from typing import Sequence
  from typing import Tuple
  from flake8 import defaults
  from flake8 import exceptions
  from flake8 import processor
  from flake8 import utils
  from flake8._compat import FSTRING_START
  from flake8.discover_files import expand_paths
  from flake8.options.parse_args import parse_args
  from flake8.plugins.finder import Checkers
  from flake8.plugins.finder import LoadedPlugin
  from flake8.style_guide import StyleGuideManager
label_desc: Use image node_id 1 to create a new Manager object  with example: obj = Manager(style_guide, plugins, argv)