irb(main):003:0> "Hello".swapcase => "hELLO"
irb(main):004:0> "HELLO".downcase => "hello"
irb(main):005:0> "hello".upcase => "HELLO"
irb(main):006:0> "hello".capitalize => "Hello"
irb(main):004:0> "HELLO".downcase => "hello"
irb(main):005:0> "hello".upcase => "HELLO"
irb(main):006:0> "hello".capitalize => "Hello"