Return tangent of a number

Contract
Return type	wob
No input parameters.

Water Contract
<method number.double.tan/>

See also: cos, acos, cosh, sin, asin, sinh, atan, tanh, atan2, radians_to_degrees, degrees_to_radians, double

Returns the tangent of a _subject of type double .

30.0.<degrees_to_radians />.<tan />

0.5773502691896257