docs: def convert_code_to_value(M_c, cidx, code):
      """
      For a column with categorical data, this function takes the 'code':
      the integer used to represent a specific value, and returns the corresponding
      raw value (e.g. 'Joe' or 234.23409), which is always encoded as a string.
  
      Note that the underlying store 'value_to_code' is unfortunately named backwards.
      TODO: fix the backwards naming.
      """
      if M_c['column_metadata'][cidx]['modeltype'] == 'normal_inverse_gamma':
          return float(code)
      else:
          try:
              return M_c['column_metadata'][cidx]['value_to_code'][int(code)]
          except KeyError:
              return M_c['column_metadata'][cidx]['value_to_code'][str(int(code))]