# File lib/mail/encodings/transfer_encoding.rb, line 30
      def self.get_best_compatible(source_encoding, str)
        if self.can_transport? source_encoding then
            source_encoding 
        else
            choices = []
            Encodings.get_all.each do |enc|
                choices << enc if self.can_transport? enc and enc.can_encode? source_encoding
            end
            best = nil 
            best_cost = 100
            choices.each do |enc|
                this_cost = enc.cost str
                if this_cost < best_cost then
                    best_cost = this_cost
                    best = enc
                elsif this_cost == best_cost then 
                    best = enc if enc::PRIORITY < best::PRIORITY
                end
            end
            best
        end
      end