{"task": {"agent_timeout": 3000, "task": "pandas-dev__pandas-49920", "verifier_timeout": 6000, "instruction": "json_normalize - incorrect removing separator from beginning of key \n```\nprint(pd.__version__)\njsn={'_id':{'a1':10,\"l2\":{\"l3\":0}}, \"gg\":4}\ndisplay(pd.json_normalize(jsn,sep='_'))\n```\n**Actual result:**\n\n\n

1.5.2\n

\n\n\u00a0 gg | id_a1 | id_l2_l3\n-- | -- | --\n4 | 10 | 0\n\n

\n\n\n\n**Expected result:**\nthe \"_\" prefix should not be removed from the beginning of the column names.\n\n\n

1.5.2\n

\n\n\u00a0 gg | _id_a1 | _id_l2_l3\n-- | -- | --\n4 | 10 | 0\n\n

\n\n\n\n**This issue was introduced with the following change:**\nhttps://github.com/pandas-dev/pandas/pull/40035/files\n", "memory": "8192m", "runnable": false, "difficulty": "hard", "language": "", "cpus": 1, "instruction_truncated": false, "category": "debugging", "compose": false, "has_solution": true, "oracle": null, "docker_image": "", "taskset": "swegym", "tags": ["debugging", "swe-bench"]}, "runs": []}