code: def cache_key_prefix(self):
      return ("#").join(self.key)
  
imports: import datetime
  from abc import ABCMeta, abstractmethod
  import lore
  from lore.env import require
  from lore.util import convert_df_columns_to_json
  import pandas
  import inflection
label_desc: Use image node_id 12 for calling the BaseFeatureExporter obj's underlying member method code with example usage: obj.cache_key_prefix() and returns: str