class_docstr: Responsible for parsing configuration from files and CLI.
  
  There are 2 types of configurations: Run configurations and Check
  configurations.
  
  Run Configurations:
  ------------------
  Responsible for deciding things that are related to the user interface and
  configuration discovery, e.g. verbosity, debug options, etc.
  All run configurations default to `False` or `None` and are decided only
  by CLI.
  
  Check Configurations:
  --------------------
  Configurations that are related to which files and errors will be checked.
  These are configurable in 2 ways: using the CLI, and using configuration
  files.
  
  Configuration files are nested within the file system, meaning that the
  closer a configuration file is to a checked file, the more relevant it will
  be. For instance, imagine this directory structure:
  
  A
  +-- tox.ini: sets `select=D100`
  +-- B
      +-- foo.py
      +-- tox.ini: sets `add-ignore=D100`
  
  Then `foo.py` will not be checked for `D100`.
  The configuration build algorithm is described in `self._get_config`.
  
  Note: If any of `BASE_ERROR_SELECTION_OPTIONS` was selected in the CLI, all
  configuration files will be ignored and each file will be checked for
  the error codes supplied in the CLI.
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docstr: Create a configuration parser.
docstr_tok: ["Create","a","configuration","parser","."]
code: def __init__(self):
      """Create a configuration parser."""
      self._cache = {}
      self._override_by_cli = None
      self._options = self._arguments = self._run_conf = None
      self._parser = self._create_option_parser()
  
imports: import copy
  import itertools
  import operator
  import os
  import sys
  from collections import namedtuple
  from collections.abc import Set
  from configparser import NoOptionError, NoSectionError, RawConfigParser
  from functools import reduce
  from re import compile
  from ._version import __version__
  from .utils import log
  from .violations import ErrorRegistry, conventions
label_desc: Use image node_id 1 to create a new ConfigurationParser object  with example: obj = ConfigurationParser()