class Haml::Exec::HamlSass

so they can run their respective programs.
This is meant to be overridden by subclasses

and requires the appropriate file.
In particular, sets `@options[:for_engine][:filename]` to the input filename
Processes the options set by the command-line arguments.

def process_result
  super
  @options[:for_engine][:filename] = @options[:filename] if @options[:filename]
  require File.dirname(__FILE__) + "/../#{@name.downcase}"
end