# File lib/rouge/guessers/glob_mapping.rb, line 6
      def self.by_pairs(mapping, filename)
        glob_map = {}
        mapping.each do |(glob, lexer_name)|
          lexer = Lexer.find(lexer_name)

          # ignore unknown lexers
          next unless lexer

          glob_map[lexer.name] ||= []
          glob_map[lexer.name] << glob
        end

        new(glob_map, filename)
      end