ruby === case中で使う
http://qiita.com/Linda_pp/items/53a527721d932b8eccce
csae b-a
when 50...Float::INFINITY #これはb-a>=50と同じ
range = 1.0...10.0
range === 1.0
# => true
range === 10.0
# => false
http://qiita.com/Linda_pp/items/53a527721d932b8eccce
csae b-a
when 50...Float::INFINITY #これはb-a>=50と同じ
range = 1.0...10.0
range === 1.0
# => true
range === 10.0
# => false