Antiderivative of hyperbolic cosecant

Theorem: The following formula holds: $$\displaystyle\int \mathrm{csch}(z)dz = \log\left(\tanh\left(\frac{z}{2}\right)\right),$$ where $\mathrm{csch}$ denotes the hyperbolic cosecant, $\log$ denotes the logarithm, and $\tanh$ denotes the hyperbolic tangent.

Proof: █