Depth first search of a tree with a per-branch "exclude" list

ex-members.py

#!/usr/bin/env python3

"""
ASN to AS-SET mapping:
AS4200000011 -> AS-A1
AS4200000021 -> AS-B1
AS4200000022 -> AS-B2
AS4200000023 -> AS-B3
AS4200000031 -> AS-C1
AS4200000032 -> AS-C2
AS4200000033 -> AS-C3
AS4200000034 -> None - leaf AS with no downstreams
"""
IRRDB = {
    "AS-A1": {
        "members": ["AS4200000011", "AS-B1", "AS-B2", "AS-B3", "AS-C1"],
        "ex-members": ["AS-B3", "AS-C3", "AS4200000034"],
    },
    "AS-B1": {
        "members": ["AS4200000021", "AS-C1", "AS-C2",],
    },
    "AS-B2": {
        "members": ["AS4200000022", "AS-C1", "AS-C3"],
        "ex-members": ["AS-C1"],
    },
    "AS-B3": {
        "members": ["AS4200000023", "AS-B2", "AS-C2"],
    },
    "AS-C1": {
        "members": ["AS4200000031"],
    },
    "AS-C2": {
        "members": ["AS4200000032", "AS4200000034"],
    },
    "AS-C3": {
        "members": ["AS4200000033", "AS4200000034"],
    },
}

as_set_list = set()
asn_list = set()

def get_members(as_set, ex_list):
    if "ex-members" in IRRDB[as_set]:
        for m in IRRDB[as_set]["ex-members"]:
            ex_list.add(m)

    if "members" in IRRDB[as_set]:
        for member in IRRDB[as_set]["members"]:
            if member in ex_list:
                continue
            elif member[:3] == "AS-":
                as_set_list.add(member)
                get_members(member, ex_list.copy())
            else:
                asn_list.add(member)

get_members("AS-A1", set(IRRDB["AS-A1"]["ex-members"]))
print(f"final asset list: {as_set_list}")
print(f"final asn list: {asn_list}")