To accept multiple inputs on one line, I know you can do something like:
a, b = input().split()
And if the user were to only type 1 input, they would come across a ValueError:
"ValueError: not enough values to unpack (expected 2, got 1)"
Therefore is there a way of allowing the user the choice to write either 1 or both inputs so that if the user were to only have 1 input, the variable b would be forgotten or replaced with a placeholder?