ArmOffTheRealLine​(AngouriMath.​Entity,​AngouriMath.​Entity[])

The sign arms choose between forms by which is real where the integrand is, and off
the real line that has nothing to go on. i < 0 and i > 0 are each
NaN, the complex numbers not being ordered, and a piecewise with no arm that holds is
NaN with them: 1/(x^2 + i) and 1/sqrt(i x^2 + 1) answered NaN + C,
and 1/sqrt(i a x^2 + 1) a piecewise that is NaN for every real a but zero.
Nor is a real sign any help where the rest of the quadratic is not real: with
E = b^2 - 4ac the arcsine differentiates back to 1/sqrt(Q) only where
sqrt(E) sqrt(Q/E) is sqrt(Q), and 1/sqrt(-x^2 + (1 + i) x + 1) came back as minus its integrand below -2. The arctangent and the logarithm use nothing about their root but
sqrt(q)^2 = q, and are antiderivatives off the real line as well.
https://github.com/asc-community/AngouriMath/issues/1598