# File lib/linecache.rb, line 110
  def clear_file_cache(filename=nil)
    if filename
      if @@file_cache[filename]
        @@file_cache.delete(filename)
      end
    else
      @@file_cache = {}
      @@file2file_remap = {}
      @@file2file_remap_lines = {}
    end
  end