code: def execute_fields_serially(
      exe_context, parent_type, source_value, fields
  ):
      def execute_field_callback(results, response_name):
          field_asts = fields[response_name]
          result = resolve_field(
              exe_context, parent_type, source_value, field_asts
          )
          if result is Undefined:
              return results
  
          if is_thenable(result):
  
              def collect_result(resolved_result):
                  results[response_name] = resolved_result
                  return results
  
              return result.then(collect_result, None)
  
          results[response_name] = result
          return results
  
      def execute_field(prev_promise, response_name):
          return prev_promise.then(
              lambda results: execute_field_callback(
                  results, response_name
              )
          )
  
      return functools.reduce(
          execute_field,
          fields.keys(),
          Promise.resolve(collections.OrderedDict()),
      )
  
imports: import collections
  from collections.abc import Iterable
  import functools
  import logging
  import sys
  from wandb_promise import Promise, promise_for_dict, is_thenable
  from ..error import GraphQLError, GraphQLLocatedError
  from ..pyutils.default_ordered_dict import DefaultOrderedDict
  from ..pyutils.ordereddict import OrderedDict
  from ..type import GraphQLEnumType, GraphQLInterfaceType, GraphQLList, GraphQLNonNull, GraphQLObjectType, GraphQLScalarType, GraphQLSchema, GraphQLUnionType
  from .base import ExecutionContext, ExecutionResult, ResolveInfo, Undefined, collect_fields, default_resolve_fn, get_field_def, get_operation_root_type
  from .executors.sync import SyncExecutor
  from .experimental.executor import execute
  from .middleware import MiddlewareManager
label_desc: Use image node_id 3 for calling a global function with example usage: execute_fields_serially(exe_context, parent_type, source_value, fields) and returns: functools, results, prev_promise, results, result, results