old_contents: class AttributeInputType:
      """The type that we expect to render the attribute's values as."""
  
      DROPDOWN = "dropdown"
      MULTISELECT = "multiselect"
      FILE = "file"
      REFERENCE = "reference"
  
      CHOICES = [
          (DROPDOWN, "Dropdown"),
          (MULTISELECT, "Multi Select"),
          (FILE, "File"),
          (REFERENCE, "Reference"),
      ]
      # list of the input types that can be used in variant selection
      ALLOWED_IN_VARIANT_SELECTION = [DROPDOWN]
  
  
  class AttributeType:
      PRODUCT_TYPE = "product-type"
      PAGE_TYPE = "page-type"
  
      CHOICES = [(PRODUCT_TYPE, "Product type"), (PAGE_TYPE, "Page type")]
  
  
  class AttributeEntityType:
      """Type of a reference entity type. Must match the name of the graphql type."""
  
      PAGE = "Page"
      PRODUCT = "Product"
  
      CHOICES = [(PAGE, "Page"), (PRODUCT, "Product")]
  
new_contents: class AttributeInputType:
      """The type that we expect to render the attribute's values as."""
  
      DROPDOWN = "dropdown"
      MULTISELECT = "multiselect"
      FILE = "file"
      REFERENCE = "reference"
  
      CHOICES = [
          (DROPDOWN, "Dropdown"),
          (MULTISELECT, "Multi Select"),
          (FILE, "File"),
          (REFERENCE, "Reference"),
      ]
      # list of the input types that can be used in variant selection
      ALLOWED_IN_VARIANT_SELECTION = [DROPDOWN]
  
  
  class AttributeType:
      PRODUCT_TYPE = "product-type"
      PAGE_TYPE = "page-type"
  
      CHOICES = [(PRODUCT_TYPE, "Product type"), (PAGE_TYPE, "Page type")]
  
  
  class AttributeEntityType:
      """Type of a reference entity type. Must match the name of the graphql type.
  
      After adding new value, `REFERENCE_VALUE_NAME_MAPPING`
      and `ENTITY_TYPE_TO_MODEL_MAPPING` in saleor/graphql/attribute/utils.py
      must be updated.
      """
  
      PAGE = "Page"
      PRODUCT = "Product"
  
      CHOICES = [(PAGE, "Page"), (PRODUCT, "Product")]
  
subject: Add info about required updates in AttributeEntityType