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 _split(self, path):
        if "/" in path:
            subdir, rest = path.split("/", 1)
        else:
            subdir, rest = path, ""
        if not subdir:
            raise error.ProgrammingError("path cannot be absolute")
        return subdir, rest