def set_roots(self, uproot_with=None):
        ''' Set the roots of the tree in the os environment

        Parameters:
            uproot_with (str):
                A new TREE_DIR path used to override an existing TREE_DIR environment variable

        '''

        # Check for TREE_DIR
        self.treedir = os.environ.get('TREE_DIR', None) if not uproot_with else uproot_with
        if not self.treedir:
            treefilepath = os.path.dirname(os.path.abspath(__file__))
            if 'python/' in treefilepath:
                self.treedir = treefilepath.rsplit('/', 2)[0]
            else:
                self.treedir = treefilepath
            self.treedir = treefilepath
            os.environ['TREE_DIR'] = self.treedir

        # Check sas_base_dir
        if 'SAS_BASE_DIR' in os.environ:
            self.sasbasedir = os.environ["SAS_BASE_DIR"]
        else:
            self.sasbasedir = os.path.expanduser('~/sas')

        # make the directories
        if not os.path.isdir(self.sasbasedir):
            os.makedirs(self.sasbasedir)
Set the roots of the tree in the os environment

        Parameters:
            uproot_with (str):
                A new TREE_DIR path used to override an existing TREE_DIR environment variable