     
     @inline(__always)
     private func send <Request: ATTProtocolDataUnit> (_ request: Request) {
-        
-        guard let connection = self.connection
-            else { return } // cannot queue after disconnection
         
         log?("Request: \(request)")
         

    
    public var writePending: (() -> ())? {
        
        get { return connection?.writePending }
        
        set { connection?.writePending = newValue }
    }
    
    public private(set) var maximumTransmissionUnit: ATTMaximumTransmissionUnit = .default {
        
        // update connection with new value
        didSet { connection?.maximumTransmissionUnit = maximumTransmissionUnit }
    }
    
    public let preferredMaximumTransmissionUnit: ATTMaximumTransmissionUnit
    
    // Don't modify
    @_versioned
    internal private(set) var connection: ATTConnection?
    
    /// Whether the client is currently writing a long value.
    internal private(set) var inLongWrite: Bool = false

        case let .error(error):
            
            log?("Could not exchange MTU: \(error)")
            
        case let .value(pdu):
            
