help -> String[permalink][rdoc]to_s -> Stringサマリの文字列を返します。
例
require "optparse"
options = {}
opts = OptionParser.new do |opts|
  opts.banner = "Usage: example.rb [options]"
  opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|
    options[:verbose] = v
  end
end
puts opts.help
# => Usage: example.rb [options]
#    -v, --[no-]verbose               Run verbosely