class ActiveFedora::Base

def generate_dsid(prefix="DS")

Example: if there are already datastreams with IDs DS1 and DS2, this method will return DS3. If you specify FOO as the prefix, it will return FOO1.
return a valid dsid that is not currently in use. Uses a prefix (default "DS") and an auto-incrementing integer 
def generate_dsid(prefix="DS")
  keys = datastreams.keys
  next_index = keys.select {|v| v =~ /(#{prefix}\d*$)/}.length + 1
  new_dsid = prefix.to_s + next_index.to_s
  # while keys.include?(new_dsid)
  #         next_index += 1
  #         new_dsid = prefix.to_s + rand(range).to_s
  #       end
end