txs and weights must be nonzero.

NewSim ..

If a block won't include any txs regardless of fee, set MinFeeRate = MaxFeeRate.

Implements BlockSource; models max block size and min fee rate as independent random variables.

The typical tx source: poisson arrivals with independent (feerate, size).

A simulation block source.

MonotonicFn represents a (non-strict) monotonic function.

A simulation tx source.