+ add Tracer test-case proposed in pr #5 - *not fixed yet, so you can see* the "indentation bug":

1..10
ok 1 - Sample.parse("x") with the tracer lives
ok 2 - Sample.subparse("x") with the tracer lives
ok 3 - Sample.new().parse("x") with the tracer lives
ok 4 - Sample.new().subparse("x") with the tracer lives
# test-case proposed in pull-request #5
ok 5 - Sample.parse("x") with the tracer lives
ok 6 - *remote-controlling* Sample.parse("boom") survives
ok 7 - Sample.parse("boom") with the tracer threw
ok 8 - Sample.parse("boom") with the tracer threw the right thing
ok 9 - Sample.parse("x") (again) with the tracer lives
not ok 10 - the two successful parses should give identical output
#      got: '|  |  TOP
# |  |  |  foo
# |  |  |  * MATCH "x"
# |  |  * MATCH "x"
# '
# expected: 'TOP
# |  foo
# |  * MATCH "x"
# * MATCH "x"
# '
# Looks like you failed 1 tests of 10