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Description
Right now canonicalizing at Tangent{T} inserts ZeroTangent for all fields of the T that don't have explict tangents recorded.
As does getproperty.
This is correct in that they don't have anything recorded as they don't get used to determine the output -- which is what ZeroTangent represents.
But it is also true for if the primal field is Char or Bool or Int or Symbol etc that they don't have a tangent space at all so NoTangent is also correct, and kinda more expected.
We can't always get it right just from the primal type, since it could be a indicator float etc.
But we can probably do pretty well