binary.rb

def strip_vowels(string, acc = "")
  return acc if string.length <= 0

  case string[0].downcase
  when "a"
    strip_vowels(string[1..-1], acc)
  when "e"
    strip_vowels(string[1..-1], acc)
  when "i"
    strip_vowels(string[1..-1], acc)
  when "o"
    strip_vowels(string[1..-1], acc)
  when "u"
    strip_vowels(string[1..-1], acc)
  else
    strip_vowels(string[1..-1], acc + string[0])
  end
end

puts strip_vowels("harry")
#=> hrry