code: def have_environment_marker_support():
      
      try:
          from pkg_resources import parse_version
          from setuptools import __version__
          return parse_version(__version__) >= parse_version('0.7.2')
      except Exception:
          return False
docs: Check whether setuptools has support for PEP-426 environment marker support.
  
      Based on the ``setup.py`` script of the ``pytest`` package:
      https://bitbucket.org/pytest-dev/pytest/src/default/setup.py