def __init__(self, package, version):
        """Construct a new requirement.

        :param package: the package name.
        :param version: a semver compatible version specification.
        """
        self.package = package
        self.version = version
        if self.version and not re.match(r"[<=>~]", version[:2]):
            self.version = "=={}".format(self.version)
def _try_write_with_flush(cls, fileobj, payload):
        """This method is here so that it can be patched to simulate write errors.

        This is because mock can't patch primitive objects like file objects.
        """
        fileobj.write(payload)
        fileobj.flush()