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{
  "errorMessage": "Cannot set a DataFrame with multiple columns to the single column ticker_prefix",
  "errorType": "ValueError",
  "requestId": "ae8d4164-b358-4d96-a4b1-cef8dcdb3ecf",
  "stackTrace": [
    "  File \"/var/task/lambda_function.py\", line 463, in lambda_handler\n    res = processor.process(persist_z_spread_table=persist_z_spread_table,\n",
    "  File \"/var/task/lambda_function.py\", line 434, in process\n    raise e\n",
    "  File \"/var/task/lambda_function.py\", line 426, in process\n    input_df = self.get_valid_mid_data(persist_z_spread_table=persist_z_spread_table,\n",
    "  File \"/var/task/lambda_function.py\", line 244, in get_valid_mid_data\n    df['ticker_prefix'] = df.apply(lambda x: x['ticker'][0:4], axis=1)\n",
    "  File \"/opt/python/pandas/core/frame.py\", line 3968, in __setitem__\n    self._set_item_frame_value(key, value)\n",
    "  File \"/opt/python/pandas/core/frame.py\", line 4123, in _set_item_frame_value\n    raise ValueError(\n"
  ]
}