docstr: Create Instance and return instance id.
docstr_tok: ["Create","Instance","and","return","instance","id","."]
code: def _create_instance(cls, hook: EC2Hook):
      """Create Instance and return instance id."""
      return cls._create_instances(hook)[0]
  
imports: from __future__ import annotations
  import pytest
  from moto import mock_ec2
  from airflow.exceptions import AirflowException
  from airflow.providers.amazon.aws.hooks.ec2 import EC2Hook
label_desc: Use image node_id 3 for calling the TestEC2Hook obj's underlying member method code with example usage: obj._create_instance(cls, hook) and returns: cls