Invalid regex when parsing ASN

[bsmith1180]

This is closely related to issue #83. The regex at line 243 in init.py is buggy.

The regex in question is

"^[AS]|[as]|[aS]|[As]][0-9]*(\.)?[0-9]+"

There's 2 issues:

• Bug A: Extra ] (an unmatched closing bracket) in [As]]
• Bug B: The Alternation Is Broken. Because | has low precedence, this means:

(^[AS]) OR ([as]) OR ([aS]) OR ([As]])

Which means:

^[AS] is anchored
The other alternatives are NOT anchored
The numeric part only applies to the last branch
So the regex does not enforce:

AS123
AS1.234

correctly.

Suggestion is to use

pattern = re.compile(r"(?i)^as\d+(\.\d+)?$")

Or simply merge the PR that has a more complete fix