Easy password hash migration from MD5 to BCrypt.

Many legacy production systems still use non-salted MD5 function for password hashing. These hashes are usually stored in the database and used for user authentication. The problem is that non-salted MD5 hash is no more secure today. There are so-called rainbow tables (precomputed MD5 hashes for word dictionaries) that can be used for easy reverse lookup.

Alexander Goldstein's Each! Pattern

class Array
 def each!
  while count > 0
   yield(shift)
  end
 end
end