Running ftplib code on remote server with Paramiko

I need to execute the below commands in the order

Step 1 (from server1): ssh server2

Step 2 (from server2): ftp server3

How can I do the same?

import paramiko
import ftplib
client = paramiko.SSHClient()
client.load_system_host_keys()
client.connect(server2)
(stdin, stdout, stderr) = client.exec_command('ftp_server = ftplib.FTP(server3, user, pass) ; ftp_server.encoding = "utf-8" ; ftp_server.cwd("xx/yy") ; file=open("aa.png", "rb") ; ftp_server.storbinary(f"STOR {"aa.png"}", file)')

The SSHClient.exec_command maps to "exec" channel of the SSH server. The "exec" channel typically runs shell commands. While you are trying to run Python code. Either use the exec_command to run ftp. Or run python with your code (if the server has python).

Though the native Python solution would be to forward the local ports and run the Python FTP code locally to against the forwarded ports. Like here:
https://stackoverflow.com/q/35304525/850848
Except that you will use nesting FTP, not SSH. But port forwarding FTP is more difficult, as you need to forward even the data ports.