Python tan(x) function calculates the tangent value of radian angle x. It's a method of math module.

>>> import math
>>> math.tan(math.pi)

-1.2246467991473532e-16

>>> math.tan(math.pi/2)

1.633123935319537e+16

>>> math.tan(math.pi/6)

0.5773502691896257

>>> math.tan(0)

0.0