[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is a polyunsaturated long-chain fatty acid with a 20-carbon backbone and exactly 2 double bonds. At least 5 different isomers can be called by this name."}, {"from": "gpt", "value": "[C][C][C][C][C][C][=C][C][C][=C][C][C][C][C][C][C][C][C][C][C][=Branch1][C][=O][O]"}]