token #0: [0-9]{4,6}
token #1: [0-9]*
token #2: \n
testing string: 123
1234
12345
123456
1234567
0

matched token #1 :123
matched token #2 :

matched token #0 :1234
matched token #2 :

matched token #0 :12345
matched token #2 :

matched token #0 :123456
matched token #2 :

matched token #1 :1234567
matched token #2 :

matched token #1 :0
matched token #2 :

testing string: 123
1234
12345
123456
1234567
0

matched token #1 :123
matched token #2 :

matched token #0 :1234
matched token #2 :

matched token #0 :12345
matched token #2 :

matched token #0 :123456
matched token #2 :

matched token #1 :1234567
matched token #2 :

matched token #1 :0
matched token #2 :