code: def clean_dataframes(dfs):
      
      if isinstance(dfs, (list)):
          for df in dfs:
              df = clean_dataframe(df)
          return dfs
      else:
          return [clean_dataframe(dfs)]
docs: Fill NaNs with the previous value, the next value or if all are NaN then 1.0
  
      TODO:
        Linear interpolation and extrapolation
  
      Arguments:
        dfs (list of dataframes): list of dataframes that contain NaNs to be removed
  
      Returns:
        list of dataframes: list of dataframes with NaNs replaced by interpolated values