code: def start_worker(
      self,
      queue_name,
      resources_needed={},
      blocking=True,
      ssh_keypair=None,
      timeout=300,
      ports=[],
  ):
      imageid = self._get_image_id()
  
      name = self._generate_instance_name()
  
      instance_type = self._select_instance_type(resources_needed)
  
      startup_script = self._get_startup_script(
          resources_needed, queue_name, timeout=timeout
      )
  
      self.logger.info(
          "Starting EC2 instance of type {}".format(instance_type)
      )
      kwargs = {
          "BlockDeviceMappings": self._get_block_device_mappings(
              resources_needed
          ),
          "ImageId": imageid,
          "InstanceType": instance_type,
          "MaxCount": 1,
          "MinCount": 1,
          "UserData": startup_script,
          "InstanceInitiatedShutdownBehavior": "terminate",
          "TagSpecifications": [
              {
                  "ResourceType": "instance",
                  "Tags": [
                      {"Key": "Name", "Value": name},
                      {"Key": "Team", "Value": "tools"},
                  ],
              }
          ],
      }
      ports = set(ports)
      if ssh_keypair is not None:
          ports.add(22)  # ssh port
      if any(ports):
          groupid = self._get_security_group(ports)
          kwargs["SecurityGroupIds"] = [groupid]
          if ssh_keypair is not None:
              kwargs["KeyName"] = ssh_keypair
  
      response = self.client.run_instances(**kwargs)
      instance_id = response["Instances"][0]["InstanceId"]
      self.logger.info("Starting instance {}".format(instance_id))
  
      if blocking:
          while True:
              try:
                  response = self.client.describe_instances(
                      InstanceIds=[instance_id]
                  )
                  instance_data = response["Reservations"][0][
                      "Instances"
                  ][0]
                  ip_addr = instance_data.get("PublicIpAddress")
                  if ip_addr:
                      print("ip address: {}".format(ip_addr))
                      return
              except BaseException as e:
                  pass
  
imports: import uuid
  import os
  import base64
  import json
  import yaml
  import six
  import filelock
  import hashlib
  import pickle
  from studio import git_util
  from studio.util import logs
  from studio.storage import storage_util
  from studio.util.gpu_util import memstr2int
  from .cloud_worker_util import insert_user_startup_script
label_desc: Use image node_id 4 for calling the EC2WorkerManager obj's underlying member method code with example usage: obj.start_worker(queue_name, resources_needed, blocking, ssh_keypair, timeout, ports) without return types