How to use the pyperformance.benchmarks.bm_deltablue.EditConstraint function in pyperformance

def change(v, new_value):
    global planner
    edit = EditConstraint(v, Strength.PREFERRED)
    edits = OrderedCollection()
    edits.append(edit)

    plan = planner.extract_plan_from_constraints(edits)

    for i in range(10):
        v.value = new_value
        plan.execute()

    edit.destroy_constraint()

name = "v%s" % i
        v = Variable(name)

        if prev is not None:
            EqualityConstraint(prev, v, Strength.REQUIRED)

        if i == 0:
            first = v

        if i == n:
            last = v

        prev = v

    StayConstraint(last, Strength.STRONG_DEFAULT)
    edit = EditConstraint(first, Strength.PREFERRED)
    edits = OrderedCollection()
    edits.append(edit)
    plan = planner.extract_plan_from_constraints(edits)

    for i in range(100):
        first.value = i
        plan.execute()

        if last.value != i:
            print("Chain test failed.")

def __init__(self, v, string):
        super(EditConstraint, self).__init__(v, string)