Hyperbolic Tangent Activation Function

$0\mathrm{.}0/2\mathrm{.}0$ points $($graded$)$

In this problem, we will recall and refamiliarize ourselves with hyperbolic tangent function, which is commonly used as an activation function in a neural network.

Recall the hyperbolic tangent function is defined as

What is the domain of $,$ i$.$e$.$ for what values of is defined?