s3_client = boto3.client(
    's3',
    aws_access_key_id=s3_access_key_id,
    aws_secret_access_key=s3_access_secret_key,
    config=Config(signature_version='s3v4')
    )

s3_resource = boto3.resource(
    's3',
    aws_access_key_id=s3_access_key_id,
    aws_secret_access_key=s3_access_secret_key,
    config=Config(signature_version='s3v4')
    )

obj = s3_client.get_object(Bucket=BucketName, Key=Key)

lines = obj['Body'].read().splitlines(True)