# File lib/bundler/resolver.rb, line 180
    def self.resolve(requirements, index, source_requirements = {}, base = [], ruby_version = nil)
      base = SpecSet.new(base) unless base.is_a?(SpecSet)
      resolver = new(index, source_requirements, base, ruby_version)
      result = resolver.start(requirements)
      SpecSet.new(result)
    end