def _consider_importhook(self, args):
ns, unknown_args = self._parser.parse_known_and_unknown_args(args)<EOL>mode = getattr(ns, "<STR_LIT>", "<STR_LIT>")<EOL>if mode == "<STR_LIT>":<EOL><INDENT>try:<EOL><INDENT>hook = _pytest.assertion.install_importhook(self)<EOL><DEDENT>except SystemError:<EOL><INDENT>mode = "<STR_LIT>"<EOL><DEDENT>else:<EOL><INDENT>self._mark_plugins_for_rewrite(hook)<EOL><DEDENT><DEDENT>_warn_about_missing_assertion(mode)<EOL>
Install the PEP 302 import hook if using assertion rewriting.

        Needs to parse the --assert=<mode> option from the commandline
        and find all the installed plugins to mark them for rewriting
        by the importhook.