class Bundler::Dsl

def github(repo, options = {})
  raise ArgumentError, "Github sources require a block" unless block_given?
  github_uri  = @git_sources["github"].call(repo)
  git_options = normalize_hash(options).merge("uri" => github_uri)
  git_source  = @sources.add_git_source(git_options)
  with_source(git_source) { yield }
end