input: Write a Python function to create an S3 bucket using boto3.
  assert create_s3_bucket('mybucket', 'us-east-1') is not None
  assert create_s3_bucket('anotherbucket', 'us-west-2') is not None
output: import boto3
  
  def create_s3_bucket(bucket_name, region):
      s3_client = boto3.client('s3', region_name=region)
      try:
          if region == 'us-east-1':
              s3_client.create_bucket(Bucket=bucket_name)
          else:
              s3_client.create_bucket(
                  Bucket=bucket_name,
                  CreateBucketConfiguration={'LocationConstraint': region}
              )
          return s3_client.head_bucket(Bucket=bucket_name)
      except Exception as e:
          print(e)
          return None