def open( spec, &block )
      return nil unless gem_file_exist?( spec )
      path = full_path_to_gem( spec )
      f = File.open( path, "rb" )
      if block_given? then
        begin
          yield f
        ensure
          f.close
        end
      else
        return f
      end
      return nil
    end
def open( spec, &block )
      return nil unless gem_file_exist?( spec )
      path = full_path_to_gem( spec )
      f = File.open( path, "rb" )
      if block_given? then
        begin
          yield f
        ensure
          f.close
        end
      else
        return f
      end
      return nil
    end
See Api#open