```ruby
require 'sfn'

module Sfn
  module Utils
    # Helper for scrubbing stack parameters
    module StackParameterScrubber

      # Validate attributes within Parameter blocks
      ALLOWED_PARAMETER_ATTRIBUTES = %w(
        Type Default NoEcho AllowedValues AllowedPattern
        MaxLength MinLength MaxValue MinValue Description
        ConstraintDescription
      )

      # Clean the parameters of the template
      #
      # @param template [Hash]
      # @return [Hash] template
      def parameter_scrub!(template)
        parameters = template['Parameters']
        if parameters
          parameters.each do |name, options|
            options.delete_if do |attribute, value|
              !ALLOWED_PARAMETER_ATTRIBUTES.include?(attribute)
            end
          end
          template['Parameters'] = parameters
        end
        template
      end
    end
  end
end
```

Change syntax to prevent rufo from dying
user
```ruby
require 'sfn'

module Sfn
  module Utils
    # Helper for scrubbing stack parameters
    module StackParameterScrubber

      # Validate attributes within Parameter blocks
      ALLOWED_PARAMETER_ATTRIBUTES = [
        'Type', 'Default', 'NoEcho', 'AllowedValues', 'AllowedPattern',
        'MaxLength', 'MinLength', 'MaxValue', 'MinValue', 'Description',
        'ConstraintDescription',
      ]

      # Clean the parameters of the template
      #
      # @param template [Hash]
      # @return [Hash] template
      def parameter_scrub!(template)
        parameters = template['Parameters']
        if parameters
          parameters.each do |name, options|
            options.delete_if do |attribute, value|
              !ALLOWED_PARAMETER_ATTRIBUTES.include?(attribute)
            end
          end
          template['Parameters'] = parameters
        end
        template
      end
    end
  end
end
```
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