code: def _process_payload(payload, key):
      payload = jsonable_encoder(payload, exclude_none=True)
  
      input_data = payload.pop(key, None)
      request_payload = {
          "inputs": input_data
          if isinstance(input_data, list)
          else [input_data]
      }
  
      if payload:
          request_payload["params"] = payload
  
      return request_payload
  
imports: import time
  from typing import List
  from fastapi import HTTPException
  from fastapi.encoders import jsonable_encoder
  from pydantic import BaseModel, StrictFloat, StrictStr, ValidationError, validator
  from mlflow.gateway.config import MlflowModelServingConfig, RouteConfig
  from mlflow.gateway.constants import MLFLOW_SERVING_RESPONSE_KEY
  from mlflow.gateway.providers.base import BaseProvider
  from mlflow.gateway.providers.utils import send_request
  from mlflow.gateway.schemas import chat, completions, embeddings
label_desc: Use image node_id 3 for calling the MlflowModelServingProvider obj's underlying member method code with example usage: obj._process_payload(payload, key) and returns: request_payload