compose_sets

# File lib/rubygems/resolver.rb, line 62
  def self.compose_sets *sets
    sets.compact!

    sets = sets.map do |set|
      case set
      when Gem::Resolver::BestSet then
        set
      when Gem::Resolver::ComposedSet then
        set.sets
      else
        set
      end
    end.flatten

    case sets.length
    when 0 then
      raise ArgumentError, 'one set in the composition must be non-nil'
    when 1 then
      sets.first
    else
      Gem::Resolver::ComposedSet.new(*sets)
    end
  end