base 62 encoding in ruby (versão funcional)

base_62.rb

ALPHABET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"     
                                                                                
def base62_encode(num, alphabet=ALPHABET)                                       
  base = alphabet.size
  char = ALPHABET[num%base,1]
  return char if num < base
  return char + base62_encode(num/base, alphabet)
end                                                                             
                                                                                
def base62_decode(string, alphabet=ALPHABET)                                    
  base = alphabet.size                                                          
  idx = alphabet.index(string[0..0])
  return idx if string.size == 1
  return idx + base62_decode(string[1..-1], alphabet) * base 
end                                                                             

puts base62_encode(0)               
puts base62_decode("0")   
puts base62_encode(128)
puts base62_decode("1F3")   
puts base62_decode(base62_encode(128))                                                                                                                  
puts base62_encode(base62_decode("1F3"))