text: import pandas as pd
  
  from .global_var import COL_STATS_KEY
  from .global_var import META_KEY
  
  
  def observe(df):
      if not isinstance(df, pd.DataFrame):
          raise TypeError('input of "observe" should be pandas dataframe')
  
      result = {
          COL_STATS_KEY: {},
          META_KEY: {},
      }
  
      return result
  