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 update(self, *args, **kwargs):
        chain = []
        for arg in args:
            if isinstance(arg, dict):
                iterator = arg.items()
            else:
                iterator = arg
            chain = itertools.chain(chain, iterator)
        if kwargs:
            chain = itertools.chain(chain, kwargs.items())
        for key, value in iterator:
            self._collection[key] = self._from_python(key, value)