issues with 'stairs' input type

Anyone running into issues using the 'stairs' function to plot the discrete step response in 2.a) of the project? The code below gives an error saying that the input to 'stairs' is an incorrect type...which I get because 'feedback' returns a formula, not a vector. Unsure what method to use for obtaining a response vector, though, and so far documentation isn't providing answers.

c = feedback(Z,1)

stairs(c)

Answer 1

[Walter Roberson]

perhaps you are looking for stepplot()