How to use the pyrsistent._pvector.pvector function in pyrsistent

# Make a dictionary of the initial data if it isn't already,
        # that will save us some job further down since we can assume no
        # key collisions
        initial = dict(initial)

    for k, v in six.iteritems(initial):
        h = hash(k)
        index = h % size
        bucket = buckets[index]

        if bucket:
            bucket.append((k, v))
        else:
            buckets[index] = [(k, v)]

    return PMap(len(initial), pvector().extend(buckets))

mutable data by convention. The main exception to this rule is that
    dict keys and set elements are often instances of mutable objects that
    support hash-by-id, which this function can't convert anyway.

    >>> freeze(set([1, 2]))
    pset([1, 2])
    >>> freeze([1, {'a': 3}])
    pvector([1, pmap({'a': 3})])
    >>> freeze((1, []))
    (1, pvector([]))
    """
    typ = type(o)
    if typ is dict:
        return pmap(dict((k, freeze(v)) for k, v in six.iteritems(o)))
    if typ is list:
        return pvector(map(freeze, o))
    if typ is tuple:
        return tuple(map(freeze, o))
    if typ is set:
        return pset(o)
    return o

def values(self):
        return pvector(self.itervalues())

def _reallocate(self, new_size):
            new_list = new_size * [None]
            buckets = self._buckets_evolver.persistent()
            for k, v in chain.from_iterable(x for x in buckets if x):
                index = hash(k) % new_size
                if new_list[index]:
                    new_list[index].append((k, v))
                else:
                    new_list[index] = [(k, v)]

            # A reallocation should always result in a dirty buckets evolver to avoid
            # possible loss of elements when doing the reallocation.
            self._buckets_evolver = pvector().evolver()
            self._buckets_evolver.extend(new_list)

def keys(self):
        return pvector(self.iterkeys())

def items(self):
        return pvector(self.iteritems())