def __call__(self, environ, start_response):
        # sanitize the path for non unix systems
        cleaned_path = environ.get('PATH_INFO', '').strip('/')
        for sep in os.sep, os.altsep:
            if sep and sep != '/':
                cleaned_path = cleaned_path.replace(sep, '/')
        path = '/'.join([''] + [x for x in cleaned_path.split('/')
                                if x and x != '..'])

        # attempt to find a loader for the file
        real_filename, file_loader = self.loader(path[1:])
        if file_loader in None:
            return self.app(environ, start_response)

        # serve the file with the appropriate name if we found it
        guessed_type = mimetypes.guess_type(real_filename)
        mime_type = guessed_type[0] or self.fallback_mimetype
        f, mtime, file_size = file_loader()

        headers = [('Date', http_date())]
        headers.append(('Cache-Control', 'public'))
        headers.extend((
            ('Content-Type', mime_type),
            ('Content-Length', str(file_size)),
            ('Last-Modified', http_date(mtime))
        ))

        start_response('200 OK', headers)
        return wrap_file(environ, f)
dataset/ETHPy150Open pecan/pecan/pecan/middleware/static.py/StaticFileMiddleware.__call__/operator `is` -> `in`