class_docstr: The element types from Google Cloud Vision API
class_docstr_tok: ["The","element","types","from","Google","Cloud","Vision","API"]
code: def child_level(self):
      child_cvt = {
          GCVFeatureType.PAGE: GCVFeatureType.BLOCK,
          GCVFeatureType.BLOCK: GCVFeatureType.PARA,
          GCVFeatureType.PARA: GCVFeatureType.WORD,
          GCVFeatureType.WORD: GCVFeatureType.SYMBOL,
          GCVFeatureType.SYMBOL: None,
      }
      return child_cvt[self]
  
imports: import io
  import os
  import json
  import warnings
  import numpy
  from cv2 import imencode
  from .base import BaseOCRAgent, BaseOCRElementType
  from ..elements import Layout, TextBlock, Quadrilateral, TextBlock
  from ..file_utils import is_gcv_available
label_desc: Use image node_id 2 for calling the GCVFeatureType obj's underlying member method code with example usage: obj.child_level() and returns: child_cvt