If you’re using monospaced fonts for writing code (please tell me you are) spaces make sure that the code will look roughly the same on everyone’s machine.

def function(paramX: str,
             paramY: str,
             paramZ: str) -> int:
  pass

If I’d used tabs, the second and third parameter might not align with the first.

Also, left-side indentation is only a small part of the overall whitespace in code. You’re adding whitespace even when you write x = y. Spaces make sure that this whitespace around the = grows in the same scale as the indentation.