scenario: STEP ASSERT <expr>
scenario: STEP ASSERT <expr>

this allows to make assertions about test environment,
for example number of received queries,
average RTT, number of performed steps etc.

ranges are in variables: `RANGE = [...]`
step is in variable: `STEP`

example:
STEP QUERY
...

; Check whether the query was received
STEP ASSERT 0 < RANGE[0].received < 2
; This fails
STEP ASSERT RANGE[0].received > 100

it also evaluates subexpressions for useful
failure information

CZ-NIC/deckard,CZ-NIC/deckard