<doocs>0449.Serialize and Deserialize BST_1.py
def dfs(root):
    if root is None:
        return
    nonlocal t
    t.append(str(root.val))
    t.append(',')
    dfs(root.left)
    dfs(root.right)
def sample_funcname ( var_1 ) :
    if var_1 is None :
        return
    nonlocal var_3
    var_3.append ( str ( var_1.val ) )
    var_3.append ( ',' )
    var_0 ( var_1.left )
    var_0 ( var_1.right )
