Memoize on just nil

  # For pretty oneliners. It just memoizes on nil, but accepts TrueClass as a value
  def memoize(&block)
    key = caller[0][/`.*'/][1..-2] # Get the method name of the caller
    @_memoized ||= {}
    @_memoized[key].nil? ? @_memoized[key] = block.call : @_memoized[key]
  end

# memoize do
#   ExpensiveOperation
# end