Python for-loop without index and item

While @toine is completly right about using _, you could also refine this by means of a list comprehension:

list_1 = [3 for _ in range(5)]

This avoids the ITM ("initialize, than modify") anti-pattern.

You can replace i with _ to make it an 'invisible' variable.

See related: What is the purpose of the single underscore "_" variable in Python?.