locate manifests and return filepaths thereof

def find_manifests(self):
        '''locate manifests and return filepaths thereof'''
        manifest_dir = mp_util.dot_mavproxy()

        ret = []
        for file in os.listdir(manifest_dir):
            try:
                file.index("manifest")
                ret.append(os.path.join(manifest_dir,file))
            except ValueError:
                pass
        return ret