How to efficiently differentiate backslash operator for sparse matrix?

Specific Domains Numerics
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11

Could you provide a simple example of how to use @grad? I was trying to do this, but it is not working.

using ReverseDiff: gradient,  @grad
minus(a,b) = a - b
@grad function minus(a, b)
  return minus(data(a), data(b)), Δ -> (Δ, -Δ)
end
@show gradient(minus, 1,1)