code: def get_children_sum(children, attr, root):
      return reduce(
          (lambda sum, childId: sum + root[childId]["meta"][attr]),
          children,
          0,
      )
  
imports: import collections
  import json
  import sys
  import uuid
  from functools import reduce
  from alembic import op
  from sqlalchemy import Column, ForeignKey, Integer, String, Table, Text
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import relationship
  from superset import db
label_desc: Use image node_id 11 for calling a global function with example usage: get_children_sum(children, attr, root) and returns: reduce