Test, validate and match regular expressions
Matches up to three trailing characters from the set #, :, >, or $ anchored at the end of a line. It is designed to detect NetApp ONTAP controller CLI prompts, which end with sequences like '::>' or '>', making it useful as a prompt-detection pattern in SSH/telnet automation tools such as Netmiko, Expect, or Ansible. Because the quantifier allows zero matches, it also succeeds on an empty string at end-of-line, so it is typically used to confirm a prompt rather than validate content.