# File lib/sup/buffer.rb, line 456
  def ask_many_with_completions domain, question, completions, default=nil
    ask domain, question, default do |partial|
      prefix, target = 
        case partial
        when /^\s*$/
          ["", ""]
        when /^(.*\s+)?(.*?)$/
          [$1 || "", $2]
        else
          raise "william screwed up completion: #{partial.inspect}"
        end

      completions.select { |x| x =~ /^#{Regexp::escape target}/i }.map { |x| [prefix + x, x] }
    end
  end