new_contents: from construct import Array, Bytes, Struct, UBInt16, UBInt32, UBInt8
  
  
  ProtocolVersion = Struct(
      "version",
      UBInt8("major"),
      UBInt8("minor")
  )
  
  Random = Struct(
      "random",
      UBInt32("gmt_unix_time"),
      Bytes("random_bytes", 28)
  )
  
  SessionID = Struct(
      "session_id",
      UBInt8("length"),
      Bytes("session_id", lambda ctx: ctx.length)
  )
  
  CipherSuites = Struct(
      "cipher_suites",
      UBInt16("length"),
      Array(lambda ctx: ctx.length / 2, Bytes("cipher_suites", 2))
  )
  
  CompressionMethods = Struct(
      "compression_methods",
      UBInt8("length"),
      Array(lambda ctx: ctx.length, UBInt8("compression_methods"))
  )
  
  ClientHello = Struct(
      "ClientHello",
      ProtocolVersion,
      Random,
      SessionID,
      CipherSuites,
      CompressionMethods,
      UBInt16("extensions_length"),
      Bytes("extensions_bytes", lambda ctx: ctx.extensions_length),
  )
  
subject: Add tentative construct format for ClientHello messages.