HI, actually i just started with python, so my skills are a little limited 
I’am building the argument line string for check_snmp with this line in the code:
arguments += "-" + arg + " " + getattr(args, arg) + " "
because arg gives the argument without the “-”. maybe change “-” to “–” would help, but than you need to determine if a “–” or a “-” is needed. I’am pretty sure there is a better solution around, maybe a python veteran has a better idea. For the debugging you could “print(arg)” whats stored in the “arg” variable to see whats the problem.