code: def create_gateway(
      self,
      instance_name: str,
      ssh_key_pub: str,
      region: str,
      project_id: str,
  ) -> LaunchedGatewayInfo:
      gcp_resources.create_gateway_firewall_rules(
          firewalls_client=self.firewalls_client,
          project_id=self.config.project_id,
      )
      # e2-micro is available in every zone
      for i in self.regions_client.list(project=self.config.project_id):
          if i.name == region:
              zone = i.zones[0].split("/")[-1]
              break
      else:
          raise ResourceNotFoundError()
  
      request = compute_v1.InsertInstanceRequest()
      request.zone = zone
      request.project = self.config.project_id
      request.instance_resource = gcp_resources.create_instance_struct(
          disk_size=10,
          image_id=gcp_resources.get_gateway_image_id(),
          machine_type="e2-micro",
          accelerators=[],
          spot=False,
          user_data=get_gateway_user_data(ssh_key_pub),
          labels={
              "owner": "dstack",
              "dstack_project": project_id,
          },
          tags=[gcp_resources.DSTACK_GATEWAY_TAG],
          instance_name=instance_name,
          zone=zone,
          service_account=None,
      )
      operation = self.instances_client.insert(request=request)
      gcp_resources.wait_for_extended_operation(
          operation, "instance creation"
      )
      instance = self.instances_client.get(
          project=self.config.project_id,
          zone=zone,
          instance=instance_name,
      )
      return LaunchedGatewayInfo(
          instance_id=instance_name,
          region=zone,  # used for instance termination
          ip_address=instance.network_interfaces[0]
          .access_configs[0]
          .nat_i_p,
      )
  
imports: from collections import defaultdict
  from typing import Callable, Dict, List, Optional, Tuple
  import google.api_core.exceptions
  import google.cloud.compute_v1
  import dstack._internal.core.backends.gcp.auth
  import dstack._internal.core.backends.gcp.resources
  from dstack._internal.core.backends.base.compute import Compute, get_gateway_user_data, get_instance_name, get_user_data
  from dstack._internal.core.backends.base.offers import get_catalog_offers
  from dstack._internal.core.backends.gcp.config import GCPConfig
  from dstack._internal.core.errors import NoCapacityError, ResourceNotFoundError
  from dstack._internal.core.models.backends.base import BackendType
  from dstack._internal.core.models.instances import InstanceAvailability, InstanceOffer, InstanceOfferWithAvailability, InstanceType, LaunchedGatewayInfo, LaunchedInstanceInfo, Resources
  from dstack._internal.core.models.runs import Job, Requirements, Run
label_desc: Use image node_id 5 for calling the GCPCompute obj's underlying member method code with example usage: obj.create_gateway(instance_name, ssh_key_pub, region, project_id) and returns: LaunchedGatewayInfo