text: from __future__ import annotations
  
  import importlib
  import sys
  import types
  import warnings
  
  from pandas.util.version import Version
  
  # Update install.rst when updating versions!
  
  VERSIONS = {
      "bs4": "4.6.0",
      "bottleneck": "1.2.1",
      "fsspec": "0.7.4",
      "fastparquet": "0.4.0",
      "gcsfs": "0.6.0",
      "lxml.etree": "4.3.0",
      "matplotlib": "2.2.3",
      "numexpr": "2.7.0",
      "odfpy": "1.3.0",
      "openpyxl": "3.0.0",
      "pandas_gbq": "0.12.0",
      "pyarrow": "0.17.0",
      "pytest": "5.0.1",
      "pyxlsb": "1.0.6",
      "s3fs": "0.4.0",
      "scipy": "1.2.0",
      "sqlalchemy": "1.2.8",
      "tables": "3.5.1",
      "tabulate": "0.8.7",
      "xarray": "0.12.3",
      "xlrd": "1.2.0",
      "xlwt": "1.3.0",
      "xlsxwriter": "1.0.2",
      "numba": "0.46.0",
  }
  
  # A mapping from import name to package name (on PyPI) for packages where
  # these two names are different.
  
  INSTALL_MAPPING = {
      "bs4": "beautifulsoup4",
      "bottleneck": "Bottleneck",
      "lxml.etree": "lxml",
      "odf": "odfpy",
      "pandas_gbq": "pandas-gbq",
      "sqlalchemy": "SQLAlchemy",
      "jinja2": "Jinja2",
  }
  
  
  def get_version(module: types.ModuleType) -> str:
      version = getattr(module, "__version__", None)
      if version is None:
          # xlrd uses a capitalized attribute name
          version = getattr(module, "__VERSION__", None)
  
      if version is None:
          raise ImportError(f"Can't determine version for {module.__name__}")
      return version
  
  
  def import_optional_dependency(
      name: str,
      extra: str = "",
      errors: str = "raise",
      min_version: str | None = None,
  ):
      """
      Import an optional dependency.
  
      By default, if a dependency is missing an ImportError with a nice
      message will be raised. If a dependency is present, but too old,
      we raise.
  
      Parameters
      ----------
      name : str
          The module name.
      extra : str
          Additional text to include in the ImportError message.
      errors : str {'raise', 'warn', 'ignore'}
          What to do when a dependency is not found or its version is too old.
  
          * raise : Raise an ImportError
          * warn : Only applicable when a module's version is to old.
            Warns that the version is too old and returns None
          * ignore: If the module is not installed, return None, otherwise,
            return the module, even if the version is too old.
            It's expected that users validate the version locally when
            using ``errors="ignore"`` (see. ``io/html.py``)
      min_version : str, default None
          Specify a minimum version that is different from the global pandas
          minimum version required.
      Returns
      -------
      maybe_module : Optional[ModuleType]
          The imported module, when found and the version is correct.
          None is returned when the package is not found and `errors`
          is False, or when the package's version is too old and `errors`
          is ``'warn'``.
      """
  
      assert errors in {"warn", "raise", "ignore"}
  
      package_name = INSTALL_MAPPING.get(name)
      install_name = package_name if package_name is not None else name
  
      msg = (
          f"Missing optional dependency '{install_name}'. {extra} "
          f"Use pip or conda to install {install_name}."
      )
      try:
          module = importlib.import_module(name)
      except ImportError:
          if errors == "raise":
              raise ImportError(msg) from None
          else:
              return None
  
      # Handle submodules: if we have submodule, grab parent module from sys.modules
      parent = name.split(".")[0]
      if parent != name:
          install_name = parent
          module_to_get = sys.modules[install_name]
      else:
          module_to_get = module
      minimum_version = min_version if min_version is not None else VERSIONS.get(parent)
      if minimum_version:
          version = get_version(module_to_get)
          if Version(version) < Version(minimum_version):
              msg = (
                  f"Pandas requires version '{minimum_version}' or newer of '{parent}' "
                  f"(version '{version}' currently installed)."
              )
              if errors == "warn":
                  warnings.warn(msg, UserWarning)
                  return None
              elif errors == "raise":
                  raise ImportError(msg)
  
      return module
  