code: def _parser_dispatch(flavor: str | None) -> type[_HtmlFrameParser]:
      """
      Choose the parser based on the input flavor.
  
      Parameters
      ----------
      flavor : str
          The type of parser to use. This must be a valid backend.
  
      Returns
      -------
      cls : _HtmlFrameParser subclass
          The parser class based on the requested input flavor.
  
      Raises
      ------
      ValueError
          * If `flavor` is not a valid backend.
      ImportError
          * If you do not have the requested `flavor`
      """
      valid_parsers = list(_valid_parsers.keys())
      if flavor not in valid_parsers:
          raise ValueError(
              f"{repr(flavor)} is not a valid flavor, valid flavors are {valid_parsers}"
          )
  
      if flavor in ("bs4", "html5lib"):
          if not _HAS_HTML5LIB:
              raise ImportError("html5lib not found, please install it")
          if not _HAS_BS4:
              raise ImportError(
                  "BeautifulSoup4 (bs4) not found, please install it"
              )
          # Although we call this above, we want to raise here right before use.
          bs4 = import_optional_dependency("bs4")  # noqa:F841
  
      else:
          if not _HAS_LXML:
              raise ImportError("lxml not found, please install it")
      return _valid_parsers[flavor]
  
imports: from __future__ import annotations
  from collections import abc
  import numbers
  import re
  from typing import TYPE_CHECKING, Iterable, Literal, Pattern, Sequence, cast
  from pandas._libs import lib
  from pandas._typing import BaseBuffer, DtypeBackend, FilePath, ReadBuffer
  from pandas.compat._optional import import_optional_dependency
  from pandas.errors import AbstractMethodError, EmptyDataError
  from pandas.util._validators import check_dtype_backend
  from pandas.core.dtypes.common import is_list_like
  from pandas import isna
  from pandas.core.indexes.base import Index
  from pandas.core.indexes.multi import MultiIndex
  from pandas.core.series import Series
  from pandas.io.common import file_exists, get_handle, is_url, stringify_path, urlopen, validate_header_arg
  from pandas.io.formats.printing import pprint_thing
  from pandas.io.parsers import TextParser
label_desc: Use image node_id 8 for calling a global function with example usage: _parser_dispatch(flavor) and returns: _valid_parsers