manually  decode  the AMF3  in  AMF0  message:
[
>>> x
'\x00\x03\x00\x00\x00\x01\x00\x04null\x00\x04/255\x00\x00\x01/\n\x00\x00\x00\x01\x11\n\x81\x13Oflex.messaging.messages.RemotingMessage\x13operation\rsource\tbody\x13messageId\x13timestamp\x11clientId\x15timeToLive\x17destination\x0fheaders\x06!statisticAllTask\x01\t\x01\x01\x06I595D8F82-7AD2-CE38-EBA6-A1BBF524E1C0\x04\x00\x01\x04\x00\x06\x17taskManager\n\x0b\x01\x15DSEndpoint\x06\x1bmy-graniteamf!DSRequestTimeout\x04\x85\xa3\x00\tDSId\x06I99853A75-B61C-4A43-A16C-DFB5E64B7FEA\x01'
>>> 
]


documents :
[

1.
Adobe Systems Inc. AMF 0 Specification Category: ActionScript Serialization   
Action Message Format -- AMF 0 

2.
Adobe Systems Inc. AMF 3 Specification Category: ActionScript Serialization  
Action Message Format -- AMF 3 


]



b'
\x00\x03 #version  --------------------------the version number is confused here: it only means : i will use avmplus-object(which means AMF3 format embeded in AMF0)  in  AMF0  
\x00\x00 #header-count
\x00\x01 #message-count
\x00\x04 #target-uri length
null     #target-uri
\x00\x04 #response-uri length
/255     #response-uri
\x00\x00\x01/ #message-length ## ord('/')= 47 hex(47) 0x2f  0x012f = 303
# [  ## the below is value-type  
\n #  -----------------------------------AMF0 value-type   strict-array-type 
\x00\x00\x00\x01 #  ----length  
\x11 ----------------value-type : avmplus-object-marker   AMF3 embeded in AMF0 
\n   ----------------object-marker AMF3 object
[
\x81\x13 ------------U29O-traits 1-0000001 0-001-0011  0000001001 = 9  member = 9
[
O ----------------class-name U29S-value 0-100111-1   100111 = int('00100111',2) = 39
flex.messaging.messages.RemotingMessage ---------- UTF8-char * 39
]
1.
[
\x13 ------------ U29S-value 0-001001-1 001001 = 9 
operation --------------------------------- UTF8-char * 9
]
2.
[
\r --------------U29S-value 0-000110-1 000110 = 6 
source  --------------------------------- UTF8-char * 6
]
3.
[
\t
body
]
4.
[
\x13
messageId
]
5.
[
\x13
timestamp
]
6.
[
\x11
clientId
]
7.
[
\x15
timeToLive
]
8.
[
\x17 00010111
destination
]
9.
[
\x0f 0-000111-1  7
headers
]
===============================================1
[
\x06 -------------string-marker
]
[
!    0-010000-1 010000 = 16
statisticAllTask
]
==================================================2
[
\x01  ----------------------null-type
]
=======================================================3
[
\t ----------------------------------------array-marker
]
[
\x01  ---------------------U29A-value = U29   0-000000-1
]
[
\x01 ---------------------UTF-8-empty
]
===========================================================4
[ 
\x06-------------string-marker
] 
[
I '0-100100-1   100100 36
595D8F82-7AD2-CE38-EBA6-A1BBF524E1C0
]
===============================================================5
[
\x04 -------------------------------------integer-marker
]
[
\x00 --------------------------------------------0
]
=================================================================6
[
\x01----------------------null-type
]
===================================================================7
[
\x04-------------------------------------integer-marker
]
[
\x00--------------------------------------------0
]
=====================================================================8
[
\x06-------------string-marker
]
[
\x17  0-001011-1
taskManager
]
=====================================================================9
\n ----------------object-marker AMF3 object
\x0b --------------0-000-1011 U29O-traits  dynamic  obj-ref-index = 0
[
\x01 ---------0-000000-1 classname 空串的ClassName就是指这个object的Class就是普通的Object类
]
{
[
\x15 ---------- 0-001010-1  ----------------UTF-8-vr
DSEndpoint
]
[
\x06 ------------value-type string-type
]
[
\x1b ---------------0-001101-1
my-graniteamf
]
}

{
[
! 16 --------------------------------------UTF-8-vr
DSRequestTimeout
]
[
\x04 -----------------value-type interg-type
]
[
\x85\xa3\x00 ----------------- 1-0000101 1-0100011 0-0000000   0 0001 01010001 10000000   015180  86400
]
}

{
[
\t   0-000100-1
DSId
]
[
\x06
]
[
I '0-100100-1   100100 36
99853A75-B61C-4A43-A16C-DFB5E64B7FEA
]
}

{
[
\x01 ----------------------------------dynamic member end
]
}
====================================================================
# ]