# File lib/rspec/core/configuration.rb, line 286
      def add_location(file_path, line_numbers)
        # Filter locations is a hash of expanded paths to arrays of line numbers
        # to match against.
        #
        filter_locations = ((self.filter || {})[:locations] ||= {})
        (filter_locations[File.expand_path(file_path)] ||= []).push(*line_numbers)
        filter_run({ :locations => filter_locations })
      end