DerivativeHoldsAtSampledPoints​(AngouriMath.​Entity,​AngouriMath.​Entity,​AngouriMath.​Entity.​Variable)

Whether the derivative of antiderivative is
integrand, numerically, at a few points in x with every other symbol pinned to a fixed value first -- pinned before the
differentiation, since sgn(f)' and |f|' are answered only where
f is shown real-valued, which a symbol that might be complex prevents and a
number does not: an answer with sgn(tanh(c + d x)) in it, right, was
unevaluable differentiated with c and d in it and threw out of the
integrator.