if r < utf8.RuneSelf {
		return r == '-' || r == '.' || r == '_' || r == '~' ||
			'0' <= r && r <= '9' ||
			'A' <= r && r <= 'Z' ||
			'a' <= r && r <= 'z'
	}
	return false
}

// importPathOK reports whether r can appear in a package import path element.
//
// Import paths are intermediate between module paths and file paths: we allow
// disallow characters that would be confusing or ambiguous as arguments to