def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
def is_user_addon(mod, user_addon_paths):
        import os

        if not user_addon_paths:
            for path in (bpy.utils.script_path_user(),
                         bpy.utils.script_path_pref()):
                if path is not None:
                    user_addon_paths.append(os.path.join(path, "addons"))

        for path in user_addon_paths:
            if bpy.path.is_subdir(mod.__file__, path):
                return True
        return False