def mask(value)
      result = ''
      value.each_char do |ch|
        case ch
        when '#' then result += randomize(0..9).to_s
        when 'A' then result += ('A'..'Z').to_a[rand(26)]
        when 'a' then result += ('a'..'z').to_a[rand(26)]
        else result += ch
        end
      end
      result
    end
def mask(value)
      result = ''
      value.each_char do |ch|
        case ch
        when '#' then result += randomize(0..9).to_s
        when 'A' then result += ('A'..'Z').to_a[rand(26)]
        when 'a' then result += ('a'..'z').to_a[rand(26)]
        else result += ch
        end
      end
      result
    end
return a value based on a mast
 The # character will be replaced with a number
 The A character will be replaced with an upper case letter
 The a character will be replaced with a lower case letter