# File lib/operator.rb, line 157
  def help_single command
    name, opts = self.class.operations.find { |name, spec| name == command }
    raise Error, "no such ditz command '#{command}'" unless name
    args = opts[:args_spec].map do |spec|
      case spec.to_s
      when /^maybe_(.*)$/
        "[#{$1}]"
      else
        "<#{spec.to_s}>"
      end
    end.join(" ")

    puts "\#{opts[:desc]}.\nUsage: ditz \#{name} \#{args}\n"
  end