Shadowing built in Python variables

Python allows you to shadow built in variables: e.g., list, dict, set, range,….This can lead to errors like 'int' object is not callable:

In [1]: range = 5

In [2]: for i in range(3):
   ...:     i * 2
   ...:
----------------------------------------------------------
TypeError                Traceback (most recent call last)
Cell In[2], line 1
----> 1 for i in range(3):
      2     i * 2

TypeError: 'int' object is not callable

Avoid shadowing built in variables with suffixes #

For example:

_range = 5

Or just avoid built in variable names altogether.

Restore built in variables in the REPL #

I’ve only been caught by the shadowing variable issue in the REPL. Instead of restarting the REPL, built in variables can be restored with del <variable_name>:

In [7]: range = 5

In [8]: del range

In [9]: for i in range(3):
   ...:     print(i * 2)
   ...:
0
2
4