def is_file_modified(self, id_, signature):
entry = self.__entries.get(id_)<EOL>if entry is None:<EOL><INDENT>raise ValueError("<STR_LIT>" % id_)<EOL><DEDENT>if entry.sig_valid:<EOL><INDENT>filesig = entry.signature<EOL><DEDENT>else:<EOL><INDENT>filesig = self._get_signature(entry)<EOL>entry.signature = filesig<EOL>entry.sig_valid = True<EOL><DEDENT>return filesig != signature<EOL>
Check if the file referred to by `id_` has been modified.