<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def Subscript(index_node):
 """A numeric or string subscript"""

    return Node(syms.trailer, [Leaf(token.LBRACE, u"["),
                               index_node,
                               Leaf(token.RBRACE, u"]")])