docs: def require_json():
      """ Load the best available json library on demand.
      """
      # Fails when "json" is missing and "simplejson" is not installed either
      try:
          import json # pylint: disable=F0401
          return json
      except ImportError:
          try:
              import simplejson # pylint: disable=F0401
              return simplejson
          except ImportError as exc:
              raise ImportError("""Please 'pip install "simplejson>=2.1.6"' (%s)""" % (exc,))