code: def xml_marshal_bucket_constraint(region):
      
      root = s3_xml.Element('CreateBucketConfiguration', {'xmlns': _S3_NAMESPACE})
      location_constraint = s3_xml.SubElement(root, 'LocationConstraint')
      location_constraint.text = region
      data = io.BytesIO()
      s3_xml.ElementTree(root).write(data, encoding=None, xml_declaration=False)
      return data.getvalue()
docs: Marshal's bucket constraint based on *region*.
  
      :param region: Region name of a given bucket.
      :return: Marshalled XML data.