====== Description ======
The tan node returns the tangent of the value of its child-node.

====== Constraints ======
  * Minimum number of child-nodes: 1
  * Maximum number of child-nodes: 1
  * Valid input range: no constraints, but must be in radians

====== Calculus ======
The tan node returns the tangent of the angle (in radians) represented by its child-node's value.

value = tan(value<sub>1</sub>)