def ensure_targets(targets):
class TargetsCheck(BaseCommand):<EOL><INDENT>def run(self):<EOL><INDENT>if skip_npm:<EOL><INDENT>log.info('<STR_LIT>')<EOL>return<EOL><DEDENT>missing = [t for t in targets if not os.path.exists(t)]<EOL>if missing:<EOL><INDENT>raise ValueError(('<STR_LIT>' % missing))<EOL><DEDENT><DEDENT><DEDENT>return TargetsCheck<EOL>
Return a Command that checks that certain files exist.

    Raises a ValueError if any of the files are missing.

    Note: The check is skipped if the `--skip-npm` flag is used.