def flatten(tup):

    elts = []

    for elt in tup:

        if isinstance(elt, tuple):

            elts = elts + flatten(elt)

        else:

            elts.append(elt)

    return elts

class Set:

    def __init__(self):

        self.elts = {}

    def __len__(self):

        return len(self.elts)

    def __contains__(self, elt):

        return self.elts.has_key(elt)

    def add(self, elt):

        self.elts[elt] = elt

    def elements(self):

        return self.elts.keys()

    def has_elt(self, elt):

        return self.elts.has_key(elt)

    def remove(self, elt):

        del self.elts[elt]

    def copy(self):

        c = Set()

        c.elts.update(self.elts)

        return c

class Stack:

    def __init__(self):

        self.stack = []

        self.pop = self.stack.pop

    def __len__(self):

        return len(self.stack)

    def push(self, elt):

        self.stack.append(elt)

    def top(self):

        return self.stack[-1]

    def __getitem__(self, index): # needed by visitContinue()

        return self.stack[index]

MANGLE_LEN = 256 # magic constant from compile.c

def mangle(name, klass):

    if not name.startswith('__'):

        return name

    if len(name) + 2 >= MANGLE_LEN:

        return name

    if name.endswith('__'):

        return name

    try:

        i = 0

        while klass[i] == '_':

            i = i + 1

    except IndexError:

        return name

    klass = klass[i:]

    tlen = len(klass) + len(name)

    if tlen > MANGLE_LEN:

        klass = klass[:MANGLE_LEN-tlen]

    return "_%s%s" % (klass, name)

def set_filename(filename, tree):

    """Set the filename attribute to filename on every node in tree"""

    worklist = [tree]

    while worklist:

        node = worklist.pop(0)

        node.filename = filename

        worklist.extend(node.getChildNodes())