old_contents: from .base import BaseModel
  
  class AgencyDocument(BaseModel):
      " Represents a document for an agency. "
      _as_is_fields = ['file']
  
new_contents: from .base import BaseModel
  
  class AgencyDocument(BaseModel):
      " Represents a document for an agency. "
      _as_is_fields = ['file', 'type']
  
subject: Add document type to agency_document