CDK (python) throws an error while I provision a Network Load Balancer, the code used and and error as follows,

Question

```
from aws_cdk import (
    aws_elasticloadbalancingv2 as elbv2,
    aws_ec2 as ec2,
    core
)

class MyStack(core.Stack):

def __init__(self, scope: core.Construct, id: str, **kwargs) -> None:
        super().__init__(scope, id, **kwargs)

vpc = ec2.Vpc(self, 'MyVpc')

nlb = elbv2.NetworkLoadBalancer(self, 'MyNlb',
            vpc=vpc,
            internet_facing=True
        )

# Add a listener to the load balancer
        nlb.add_listener('MyListener',
            port=80,
            open=True
        )
```
ERROR:
ImportError: cannot import name 'core' from 'aws_cdk' (/home/gowtham/cdk_workshop/.venv/lib/python3.10/site-packages/aws_cdk/__init__.py)

Answer

Hello.

I think it's probably because I'm using version 2 of CDK.  
https://aws.amazon.com/jp/blogs/developer/experimental-construct-libraries-are-now-available-in-aws-cdk-v2/

I think the error occurred because the core module disappeared in CDK version 2.  
https://docs.aws.amazon.com/cdk/v2/guide/migrating-v2.html  
> AWS CDK v2 consolidates the stable parts of the AWS Construct Library, including the core library, into a single package, aws-cdk-lib. Developers no longer need to install additional packages for the individual AWS services they use. This single-package approach also means that you don't have to synchronize the versions of the various CDK library packages.

So I think you need to do something like this:  
```
from aws_cdk import (
    aws_elasticloadbalancingv2 as elbv2,
    aws_ec2 as ec2
)
from constructs import Construct
```

CDK (python) throws an error while I provision a Network Load Balancer, the code used and and error as follows,

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