```ruby
require "optparse"
require "ostruct"

module Bcu
  class << self; attr_accessor :options; end

  def self.parse!(args)
    options = OpenStruct.new
    options.all = false
    options.cask = nil
    options.cleanup = false
    options.dry_run = true

    parser = OptionParser.new do |opts|
      opts.banner = "Usage: brew cu [CASK] [options]"

      opts.on("-a", "--all", "Force upgrade outdated apps including those marked as latest and those that auto-update") do
        options.all = true
      end

      opts.on("--cleanup", "Cleans up cached downloads and tracker symlinks after updating") do
        options.cleanup = true
      end

      opts.on("-y", "--yes", "Update all outdated apps; answer yes to updating packages") do
        options.dry_run = false
      end

      # `-h` is not available since the Homebrew hijacks it.
      opts.on_tail("--h", "Show this message") do
        puts opts
        exit
      end
    end

    parser.parse!(args)

    options.cask = args[0]

    self.options = options
  end
end
```

Add `brew cu help` command
user
```ruby
require "optparse"
require "ostruct"

module Bcu
  class << self; attr_accessor :options; end

  def self.parse!(args)
    options = OpenStruct.new
    options.all = false
    options.cask = nil
    options.cleanup = false
    options.dry_run = true

    parser = OptionParser.new do |opts|
      opts.banner = "Usage: brew cu [CASK] [options]"

      opts.on("-a", "--all", "Force upgrade outdated apps including those marked as latest and those that auto-update") do
        options.all = true
      end

      opts.on("--cleanup", "Cleans up cached downloads and tracker symlinks after updating") do
        options.cleanup = true
      end

      opts.on("-y", "--yes", "Update all outdated apps; answer yes to updating packages") do
        options.dry_run = false
      end

      # `-h` is not available since the Homebrew hijacks it.
      opts.on_tail("--h", "Show this message") do
        puts opts
        exit
      end
    end

    parser.parse!(args)

    if args[0] == "help"
      puts parser
      exit
    end

    options.cask = args[0]

    self.options = options
  end
end
```
assistant