code: def create_attachment(cls, session, attachment):
          
          return super(Conversations, cls).create(
              session,
              attachment,
              endpoint_override='/attachments.json',
              out_type=Attachment,
          )
docs: Create an attachment.
  
          An attachment must be sent to the API before it can be used in a
          thread. Use this method to create the attachment, then use the
          resulting hash when creating a thread.
  
          Note that HelpScout only supports attachments of 10MB or lower.
  
          Args:
              session (requests.sessions.Session): Authenticated session.
              attachment (helpscout.models.Attachment): The attachment to be
               created.
  
          Returns:
              helpscout.models.Attachment: The newly created attachment (hash
               property only). Use this hash when associating the attachment with
               a new thread.