old_contents: from __future__ import unicode_literals
  from werkzeug.exceptions import BadRequest
  from jinja2 import Template
  
  
  class UnformattedGetAttTemplateException(Exception):
      description = 'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt'
      status_code = 400
  
  
  class ValidationError(BadRequest):
      def __init__(self, name_or_id, message=None):
          if message is None:
              message="Stack:{0} does not exist".format(name_or_id),
  
          template = Template(ERROR_RESPONSE)
          super(ValidationError, self).__init__()
          self.description = template.render(
              code="ValidationError",
              message=message,
          )
  
  
  class MissingParameterError(BadRequest):
      def __init__(self, parameter_name):
          template = Template(ERROR_RESPONSE)
          super(MissingParameterError, self).__init__()
          self.description = template.render(
              code="Missing Parameter",
              message="Missing parameter {0}".format(parameter_name),
          )
  
  
  ERROR_RESPONSE = """<ErrorResponse xmlns="http://cloudformation.amazonaws.com/doc/2010-05-15/">
    <Error>
      <Type>Sender</Type>
      <Code>{{ code }}</Code>
      <Message>{{ message }}</Message>
    </Error>
    <RequestId>cf4c737e-5ae2-11e4-a7c9-ad44eEXAMPLE</RequestId>
  </ErrorResponse>
  """
  
new_contents: from __future__ import unicode_literals
  from werkzeug.exceptions import BadRequest
  from jinja2 import Template
  
  
  class UnformattedGetAttTemplateException(Exception):
      description = 'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt'
      status_code = 400
  
  
  class ValidationError(BadRequest):
      def __init__(self, name_or_id, message=None):
          if message is None:
              message="Stack with id {0} does not exist".format(name_or_id)
  
          template = Template(ERROR_RESPONSE)
          super(ValidationError, self).__init__()
          self.description = template.render(
              code="ValidationError",
              message=message,
          )
  
  
  class MissingParameterError(BadRequest):
      def __init__(self, parameter_name):
          template = Template(ERROR_RESPONSE)
          super(MissingParameterError, self).__init__()
          self.description = template.render(
              code="Missing Parameter",
              message="Missing parameter {0}".format(parameter_name),
          )
  
  
  ERROR_RESPONSE = """<ErrorResponse xmlns="http://cloudformation.amazonaws.com/doc/2010-05-15/">
    <Error>
      <Type>Sender</Type>
      <Code>{{ code }}</Code>
      <Message>{{ message }}</Message>
    </Error>
    <RequestId>cf4c737e-5ae2-11e4-a7c9-ad44eEXAMPLE</RequestId>
  </ErrorResponse>
  """
  
subject: Fix the CloudFormation ValidationError message (#788)