Double-tokenizing a RegionSet will result in no tokens

[nleroy917]

Here is an interesting one:

>>> from gtars.tokenizers import TreeTokenizer
>>> from gtars.models import RegionSet, Region
>>> 
>>> tokenizer = TreeTokenizer("/Users/nathanleroy/Desktop/universe.bed")
>>> rs = RegionSet("/Users/nathanleroy/Desktop/test.bed")
>>> 
>>> tokens = tokenizer(rs)
>>> len(tokens)
12
>>> 
>>> tokens = tokenizer(rs)
>>> len(tokens)
0

If you try to tokenize a RegionSet twice, you get tokens the first time, then no tokens the second time. I really dont know why this is the case. I confirmed that this happens in the latest version of gtars on PyPi.

[nleroy917]

This is specific to the RegionSet object/struct. This doesn't occur with these two calls:

rs = "/Users/nathanleroy/Desktop/test.bed"
tokens = tokenizer(rs)

rs = [Region("chr1", 1, 10), Region("chr1", 5, 15)]
tokens = tokenizer(rs)