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 visitdir(self, dir):
        dir = normalizerootdir(dir, "visitdir")
        if self._prefix and dir in self._fileset:
            return "all"
        if not self._prefix:
            return True
        return (
            dir in self._fileset
            or dir in self._dirs
            or any(parentdir in self._fileset for parentdir in util.finddirs(dir))
        )