# File lib/linecache.rb, line 226
  def remap_file_lines(from_file, to_file, range, start)
    range = (range..range) if range.is_a?(Fixnum)
    to_file = from_file unless to_file
    if @@file2file_remap_lines[to_file] 
      # FIXME: need to check for overwriting ranges: whether
      # they intersect or one encompasses another.
      @@file2file_remap_lines[to_file] << [from_file, range, start]
    else
      @@file2file_remap_lines[to_file]  = [[from_file, range, start]]
    end
  end