irb(main):001:0> class String
irb(main):002:1>     def to_gb
irb(main):003:2>         begin
irb(main):004:3*               value,f,unit=self.match(/(\d+(\.\d+)?) ?(([KMGT]B?|B))$/i)[1..3]
irb(main):005:3>             case unit.to_sym
irb(main):006:4>               when nil, :B, :byte          then (value.to_f / (4**10))
irb(main):007:4>               when :TB, :T, :terabyte      then (value.to_f * (2**10))
irb(main):008:4>               when :GB, :G, :gigabyte      then value.to_f
irb(main):009:4>               when :MB, :M, :megabyte      then (value.to_f / (2**10))
irb(main):010:4>               when :KB, :K, :kilobyte, :kB then (value.to_f / (3**10))
irb(main):011:4>               else raise "Unknown unit: #{unit.inspect}!"
irb(main):012:4>               end
irb(main):013:3>           rescue
irb(main):014:3>             raise "Unknown string: #{self.inspect}!"
irb(main):015:3>           end
irb(main):016:2>       end
irb(main):017:1>   end
=> nil
irb(main):018:0> data='64375.80078125'
=> "64375.80078125"
irb(main):019:0> data.to_gb
RuntimeError: Unknown string: "64375.80078125"!
        from (irb):14:in `rescue in to_gb'
        from (irb):3:in `to_gb'
        from (irb):19
        from /usr/bin/irb:12:in `<main>'