def versions_for(gem)
      available = @versions_file.versions_for(gem.name)
      return [available.last] if gem.only_latest?

      versions = available.select do |v|
        gem.requirement.satisfied_by?(v[0])
      end

      versions = [available.last] if versions.empty?

      versions
    end
def versions_for(gem)
      available = @versions_file.versions_for(gem.name)
      return [available.last] if gem.only_latest?

      versions = available.select do |v|
        gem.requirement.satisfied_by?(v[0])
      end

      versions = [available.last] if versions.empty?

      versions
    end
Returns an Array containing the versions that should be fetched for a
 Gem.

 @param [Gemirro::Gem] gem
 @return [Array]