NameError: name 'tf' is not defined code example

Example 1: NameError: name 'fenetre' is not defined

NameError: name 'fenetre' is not defined

Example 2: NameError: name 'array' is not defined

import numpy as np

a = np.array([1,8,3])

Example 3: NameError: name 'ggt' is not defined

It is quite clear in the error, the variable isn't defined