Insufficient connected output ports

I am sorry, the subject of previous post is wrong cause I solved that
problem meanwhile, but I forgot to change it in the draft.

This is a bit frustrating situation, and I don’t know how to solve the
problem. I tried to figure out what’s going on, and wanted to call
function
input_signaturehttp://gnuradio.org/doc/doxygen-3.6/classgr__basic__block.html#a58f6d05e85931200f3771d3e50741281()
from python i norder to see what is the actual output signature but
this
function can’t be called. I also couldn’t find right explanatoin for
port
problem.
Any suggestions?

Nemanja

Thank you Marcus, this works.