code: def dtypes(self):
      df = self._raw_data
      dtypes = df[self.key + self._values].dtypes.to_frame("dtype")
      dtypes = dtypes["dtype"].astype(str).to_dict()
      return dtypes
  
file_path: lore/lore/features/db.py
imports: from abc import ABCMeta
  from datetime import datetime
  import lore.io
  from lore.features.base import BaseFeatureExporter, BaseFeatureImporter
  import lore.metadata
  from lore.metadata import FeatureMetaData
  from sqlalchemy.orm import sessionmaker, scoped_session
  import pandas
  from lore.util import convert_df_columns_to_json
  import json
label_desc: Use image node_id 3 for calling the DBFeatureExporter obj's underlying member method code with example usage: obj.dtypes() and returns: dtypes