class_docstr: This builder class ultimately constructs a TaskFlow task which is run at
  runtime (task execution time). This task generates and stores the test ENV_ID as well
  as any external resources requested (e.g.g IAM Roles, VPC, etc)
class_docstr_tok: ["This","builder","class","ultimately","constructs","a","TaskFlow","task","which","is","run","at","runtime","(","task","execution","time",")",".","This","task","generates","and","stores","the","test","ENV_ID","as","well","as","any","external","resources","requested","(","e.g.g","IAM","Roles",",","VPC",",","etc",")"]
docstr: Build and return a TaskFlow task which will create an env_id and
  fetch requested variables. Storing everything in xcom for downstream
  tasks to use.
docstr_tok: ["Build","and","return","a","TaskFlow","task","which","will","create","an","env_id","and","fetch","requested","variables",".","Storing","everything","in","xcom","for","downstream","tasks","to","use","."]
code: def build(self):
      """Build and return a TaskFlow task which will create an env_id and
      fetch requested variables. Storing everything in xcom for downstream
      tasks to use."""
  
      @task
      def variable_fetcher(ti=None):
          ti.xcom_push(ENV_ID_KEY, self.env_id)
          for variable in self.variables:
              ti.xcom_push(variable.name, variable.get_value())
  
      return variable_fetcher
  
imports: from __future__ import annotations
  import inspect
  import json
  import logging
  import os
  import time
  from pathlib import Path
  from typing import TYPE_CHECKING
  from uuid import uuid4
  import boto3
  from botocore.exceptions import ClientError, NoCredentialsError
  from airflow.decorators import task
  from airflow.providers.amazon.aws.hooks.ssm import SsmHook
  from airflow.utils.state import State
  from airflow.utils.trigger_rule import TriggerRule
label_desc: Use image node_id 3 for calling the SystemTestContextBuilder obj's underlying member method code with example usage: obj.build() and returns: variable_fetcher