Defining a local variable or function with the same name as a built-in object makes the built-in object unusable within the current scope and makes the code prone to bugs.

Bad practice

dict = {}  # dict is a Python builtin!
for idx, student in enumerate(students):
    dict[student] = idx

Preferred:

roll_number = {}
for idx, student in enumerate(students):
    roll_number[student] = idx