Custom error types for HoloFuel transactions
Implements fee calculation. The fee structure of HoloFuel may change over time, but not between
roll-outs of new HoloFuel DNAs. Therefore, its values and limits can be hard-coded here.
The HoloFuel Fuel type and math functions, and JSON serialization support. Supports Fraction
type for computing fractional HoloFuel amounts using rational numbers; useful for expressing
“percentages” of HoloFuel amounts without losing (too much) precision, while retaining the
ability to compute HoloFuel transaction fees on the largest possible transaction amounts.