Facing errors in optional lab

Hi everyone,
When I run The optional lab’s codes I face such this Errors:
NameError Traceback (most recent call last)
----> 1 plot_cost_i_w(X_train, y_train, hist)

NameError: name ‘plot_cost_i_w’ is not defined

and I can’t see the plots and results. What is the problem and how can I solve that?

Hello @M_Rezaeemanesh
You need to run all the cells before this cell from beginning.

Thank you so much