code: def _impute(df: DataFrame, num_cols: List) -> DataFrame:
      for col in num_cols:
          df[col] = df[col].fillna(df[col].median())
      return df
  
file_path: lightning-flash/src/flash/tabular/classification/utils.py
imports: import logging
  from typing import Dict, List, Tuple
  import numpy
  from flash.core.utilities.imports import _PANDAS_AVAILABLE
label_desc: Use image node_id 1 for calling a global function with example usage: _impute(df, num_cols) and returns: df