I'm using Ruby 1.8.7 patchlevel 249

Is there a more idiomatic way to do the following?

var = hash[key].nil? ? nil : hash[key].downcase

Note that if hash[key] is nil, I want nil assigned to var, so this
won't work:

var = hash[key].downcase unless hash[key].nil?

Obviously I could do this, but I'm trying to keep it on one line:

var = hash[key]
var = var.downcase unless var.nil?

-- 
Charles Calvert
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