The image is a bit difficult to read. The error appears to be thrown with the step call. This may likely be due to your having named a variable ‘step’.
Run this from a script or your Command Window:
which step -all
if the first entry is:
step is a variable.
you have found the problem. The solution is to name it something else that is relevant in the context of your code.
If that is not the problem, please provide more details.