def load_installed_version(self):
        installed_packages = get_installed_pypackages()
        if self.package in installed_packages:
            self.version = "=={}".format(
                installed_packages[self.package].version)
def myfunc(first, second=None, third=Optional(5), fourth=Optional(execute=list)):
            #Equivalent: second = deoption(second, 5)
            if isinstance(second, type(None)):
                second = 5