new sats created in every block is cut in half.

- *Cycles*: Every six halvings, something magical happens: the halving and the
  difficulty adjustment coincide. This is called a conjunction, and the time
  period between conjunctions a cycle. A conjunction occurs roughly every 24
  years. The first conjunction should happen sometime in 2032.

This gives us the following rarity levels:

- `common`: Any sat that is not the first sat of its block
- `uncommon`: The first sat of each block
- `rare`: The first sat of each difficulty adjustment period
- `epic`: The first sat of each halving epoch
- `legendary`: The first sat of each cycle
- `mythic`: The first sat of the genesis block

Which brings us to degree notation, which unambiguously represents an ordinal
number in a way that makes the rarity of a satoshi easy to see at a glance:

```
A°B′C″D‴
│ │ │ ╰─ Index of sat in the block
│ │ ╰─── Index of block in difficulty adjustment period
│ ╰───── Index of block in halving epoch
╰─────── Cycle, numbered starting from 0