How to make a Twitter list from a list of tweeps someone is following using ruby and twitter gem

make_following_list.rb

require 'rubygems'
require 'twitter'

follower  = ARGV[0] || raise("USAGE: #$0 <follower_name> [list_name]")
list_name = ARGV[1] || ("FollowedBy" + follower.upcase)

# Requires read-write token
CONSUMER_KEY    = YOUR_CONFIG_HERE
CONSUMER_SECRET = YOUR_CONFIG_HERE
OAUTH_TOKEN     = YOUR_CONFIG_HERE
OAUTH_SECRET    = YOUR_CONFIG_HERE

MAXLEN_LIST_NAME = 25

# Be gentle with Twitter API
# (your mileage may vary)
API_CHUNK_SIZE = 10
API_LOOP_DELAY = 3
MAX_RETRY      = 3

Twitter.configure do |config|
  config.consumer_key       = CONSUMER_KEY
  config.consumer_secret    = CONSUMER_SECRET
  config.oauth_token        = OAUTH_TOKEN
  config.oauth_token_secret = OAUTH_SECRET
end

Twitter.list_create(list_name.slice(0,MAXLEN_LIST_NAME))

tweeps = Twitter.friend_ids(follower).collection
puts "Adding #{tweeps.size} tweeps"

added = 0
until tweeps.empty?
  chunked_tweeps = tweeps.slice!(0,API_CHUNK_SIZE)
  tries = 0
  begin
    tries += 1
    Twitter.list_add_members(list_name,chunked_tweeps)
    added += 1
    print '.'
    STDOUT.flush
    sleep API_LOOP_DELAY
  rescue
    print 'x'
    STDOUT.flush
    sleep API_LOOP_DELAY
    retry if tries < MAX_RETRY
  end
end
puts "\nAdded #{added} tweeps"