Python subprocess arguments

Question

How do I use variable inside subprocess arguments
like:
iface = "wlan1"
cmd = subprocess.run(['iwconfig ' + iface + "' | grep 'Mode' '"] )
it's giving me errors

Answer 1

What errors? And it may be the arguments supplied
it should be a list of them all seperately.
Also, check this out: https://stackoverflow.com/questions/13332268/how-to-use-subprocess-command-with-pipes