[{"from": "human", "value": "Generate a molecule based on this description. The molecule is a diester, a methyl ester and a member of dicarboxylic acids and O-substituted derivatives. It is functionally related to an oxalic acid."}, {"from": "gpt", "value": "[C][O][C][=Branch1][C][=O][C][=Branch1][C][=O][O][C]"}]