code: def precompile(self, content, kind=None, elem=None, filename=None,
                 charset=None, **kwargs):
      
      if not kind:
          return False, content
      attrs = self.parser.elem_attribs(elem)
      mimetype = attrs.get("type", None)
      if mimetype is None:
          return False, content
  
      filter_or_command = self.precompiler_mimetypes.get(mimetype)
      if filter_or_command is None:
          if mimetype in ("text/css", "text/javascript"):
              return False, content
          raise CompressorError("Couldn't find any precompiler in "
                                "COMPRESS_PRECOMPILERS setting for "
                                "mimetype '%s'." % mimetype)
  
      mod_name, cls_name = get_mod_func(filter_or_command)
      try:
          mod = import_module(mod_name)
      except (ImportError, TypeError):
          filter = CachedCompilerFilter(
              content=content, filter_type=self.type, filename=filename,
              charset=charset, command=filter_or_command, mimetype=mimetype)
          return True, filter.input(**kwargs)
      try:
          precompiler_class = getattr(mod, cls_name)
      except AttributeError:
          raise FilterDoesNotExist('Could not find "%s".' % filter_or_command)
      filter = precompiler_class(
          content, attrs=attrs, filter_type=self.type, charset=charset,
          filename=filename, **kwargs)
      return True, filter.input(**kwargs)
docs: Processes file using a pre compiler.
      This is the place where files like coffee script are processed.