# File lib/moneta/adapters/file.rb, line 64
      def increment(key, amount = 1, options = {})
        path = store_path(key)
        FileUtils.mkpath(::File.dirname(path))
        ::File.open(path, ::File::RDWR | ::File::CREAT) do |f|
          Thread.pass until f.flock(::File::LOCK_EX)
          content = f.read
          amount += Utils.to_int(content) unless content.empty?
          content = amount.to_s
          f.pos = 0
          f.write(content)
          f.truncate(content.bytesize)
          amount
        end
      end