import csv
import gc
import sys

global var

var = []

class Fin:
    def __init__(self, name):
        self.name = name

    def __del__(self):
        var.append(self.name)

csv.unix_dialect.f = Fin("unix_dialect")

# delete all references to the module
del csv
del sys.modules["csv"]

# trigger garbage collection
gc.collect()

assert("unix_dialect" in var)