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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def s3(ctx, bucket_name, data_file, region):
 """Use the S3 SWAG backend."""

    if not ctx.data_file:
        ctx.data_file = data_file

    if not ctx.bucket_name:
        ctx.bucket_name = bucket_name

    if not ctx.region:
        ctx.region = region

    ctx.type = 's3'