def fetch(username, realm)
      return nil unless has_entry?(username, realm)
      ir = internal_record(username, realm)
      return ir['entry'].dup
    end
def fetch(username, realm)
      return nil unless has_entry?(username, realm)
      ir = internal_record(username, realm)
      return ir['entry'].dup
    end
Public: Returns the given DigestEntry from the file.

 Updating the DigestEntry instance returned by this method will NOT update
 the file. To update the file, use #update and #save!

 username - the username of the entry
 realm    - the realm of the entry

 Examples

   entry = digest_file.fetch("myuser", "myrealm")

 Returns a DigestEntry if the entry is found
 Returns nil if the entry is not found