text: 0       4   on_llm_start  OpenAI     1       1     0       0         0             0       5   on_llm_start  OpenAI     1       1     0       0         0             0       6     on_llm_end     NaN     2       1     1       0         0             0       7     on_llm_end     NaN     2       1     1       0         0             0       8     on_llm_end     NaN     2       1     1       0         0             0       9     on_llm_end     NaN     2       1