code: def check_dataframe_for_duplicate_records(obs_id_col, alt_id_col, df):
      
      if df.duplicated(subset=[obs_id_col, alt_id_col]).any():
          msg = "One or more observation-alternative_id pairs is not unique."
          raise ValueError(msg)
  
      return None
docs: Checks a cross-sectional dataframe of long-format data for duplicate
      observations. Duplicate observations are defined as rows with the same
      observation id value and the same alternative id value.
  
      Parameters
      ----------
      obs_id_col : str.
          Denotes the column in `df` that contains the observation ID
          values for each row.
      alt_id_col : str.
          Denotes the column in `df` that contains the alternative ID
          values for each row.
      df : pandas dataframe.
          The dataframe of long format data that is to be checked for duplicates.
  
      Returns
      -------
      None.