Free Hero Mesh

{mod <number> <number>}
  Modulo.

{version <number>}
  Expands into nothing. The number must be zero, otherwise it is an error.
  Future versions of Free Hero Mesh may change this.

All arithmetic/bitwise macros also allow their arguments to be directions
and keys, in which case they are treated as the corresponding numbers.

It is possible to implement a tag system in this preprocessor, which makes
it Turing complete. For example:

  {define "skip" {call \2}}
  {define "1" {skip \1|"3"|"3"|"2"|"1"|"H"}}
  {define "2" {skip \1|"3"|"3"|"1"}}