unless

unless

An unless evaluates the then branch if its condition is falsey , and evaluates the else branch, if there‘s any, otherwise. That is, it behaves in the opposite way of an if:

unless some_condition
  expression_when_falsey
else
  expression_when_truthy
end

## The above is the same as:
if some_condition
  expression_when_truthy
else
  expression_when_falsey
end

## Can also be written as a suffix
close_door unless door_closed?