code: def resolve_filename(self, package_dir, filename):
          
          sass_path = os.path.join(package_dir, self.sass_path, filename)
          if self.strip_extension:
              filename, _ = os.path.splitext(filename)
          css_filename = filename + '.css'
          css_path = os.path.join(package_dir, self.css_path, css_filename)
          return sass_path, css_path
docs: Gets a proper full relative path of Sass source and
          CSS source that will be generated, according to ``package_dir``
          and ``filename``.
  
          :param package_dir: the path of package directory
          :type package_dir: :class:`str`, :class:`basestring`
          :param filename: the filename of Sass/SCSS source to compile
          :type filename: :class:`str`, :class:`basestring`
          :returns: a pair of (sass, css) path
          :rtype: :class:`tuple`