# File lib/backports/1.9.1/enumerator/new.rb, line 34
    def initialize_with_optional_block(*arg, &block)
      return initialize_without_optional_block(*arg, &nil) unless arg.empty?  # Ruby 1.9 apparently ignores the block if any argument is present
      initialize_without_optional_block(GeneratorBP.new(&block))
    end