code: def find_customer(cls, session, mailbox, customer):
          
          return cls(
              '/mailboxes/%d/customers/%s/conversations.json' % (
                  mailbox.id, customer.id,
              ),
              session=session,
          )
docs: Return conversations for a specific customer in a mailbox.
  
          Args:
              session (requests.sessions.Session): Authenticated session.
              mailbox (helpscout.models.Mailbox): Mailbox to search.
              customer (helpscout.models.Customer): Customer to search for.
  
          Returns:
              RequestPaginator(output_type=helpscout.models.Conversation):
                  Conversations iterator.