struct subid:

One element of an OID.  Consists of text name, integer, or both.
(-1, NULL -> not present.)

struct node:

Linked list of nodes.
- label:  Nodes textual name
- subid:  Nodes subid
- parent: Nodes textual parent name
- type:   Node type
- enum:   Optional list of enumerated data

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Current parser:
- Load all nodes into linked list
- Call build_tree

get_token()