Module var 

Input variables to math expressions

A Var maintains a persistent identity from Tree to Context (where it is wrapped in a Op::Input) to evaluation (where Tape::vars maps from Var to index in the argument list).

Structs

VarIndex

Type for a variable index (implemented as a u64), used in Var::V

VarMap

Map from Var to a particular index

Enums

Var

The Var type is an input to a math expression