def dummy_edge(data):
    pass

def increment_a_edge(data):
    data['a'] += 1

def increment_a_array_edge(data):
    for i in range(len(data['a'])):
        data['a'][i] += 1

def increment_b_edge(data):
    data['b'] += 1

def decrement_a_edge(data):
    data['a'] -= 1

def nonzero_predicate(data):
    return True if data['a'] != 0 else False

def positiveness_predicate(data):
    return True if data['a'] > 0 else False

def nonpositiveness_predicate(data):
    return True if data['a'] <= 0 else False