code: def channel_close(
              self,
              registry_address: PaymentNetworkID,
              token_address: TokenAddress,
              partner_address: Address,
              retry_timeout: NetworkTimeout = DEFAULT_RETRY_TIMEOUT,
      ):
          
          self.channel_batch_close(
              registry_address=registry_address,
              token_address=token_address,
              partner_addresses=[partner_address],
              retry_timeout=retry_timeout,
          )
docs: Close a channel opened with `partner_address` for the given
          `token_address`.
  
          Race condition, this can fail if channel was closed externally.