TODO

- Move the properties from the shelley spec over in an appropriate
  way. In particular, Lemma 15.2 can be adopted by adding a forged
  value to a block.

- Finalize `valueSize`. We need to decide if it should count the
  number of pid's. The tradeoff here is accuracy vs. ease of
  explanation. Without counting the pid's, one can increase the size
  of a Value by roughly a factor of 2 over what we count, which
  weakens the protection against attacks somewhat (but the attacker
  has to supply lots of scripts in their transaction, increasing the
  txsize, which might compensate for this a bit). However, there is
  some value in keeping the minValue calculation as easy as possible,
  and having 'some constant amount plus some amount for every non-ada
  token' is easily understood.

- Decide what to do with the MPS language