code: def _create_project_ssh_key_pair(project, public_key, ssh_user):
      
  
      key_parts = public_key.split(" ")
  
      # Sanity checks to make sure that the generated key matches expectation
      assert len(key_parts) == 2, key_parts
      assert key_parts[0] == "ssh-rsa", key_parts
  
      new_ssh_meta = "{ssh_user}:ssh-rsa {key_value} {ssh_user}".format(
          ssh_user=ssh_user, key_value=key_parts[1])
  
      common_instance_metadata = project["commonInstanceMetadata"]
      items = common_instance_metadata.get("items", [])
  
      ssh_keys_i = next(
          (i for i, item in enumerate(items) if item["key"] == "ssh-keys"), None)
  
      if ssh_keys_i is None:
          items.append({"key": "ssh-keys", "value": new_ssh_meta})
      else:
          ssh_keys = items[ssh_keys_i]
          ssh_keys["value"] += "\n" + new_ssh_meta
          items[ssh_keys_i] = ssh_keys
  
      common_instance_metadata["items"] = items
  
      operation = compute.projects().setCommonInstanceMetadata(
          project=project["name"], body=common_instance_metadata).execute()
  
      response = wait_for_compute_global_operation(project["name"], operation)
  
      return response
docs: Inserts an ssh-key into project commonInstanceMetadata