The builtin math library defines attribute tau whose value is equal to the mathematical constant Tau.  Tau is defined as the ratio of the circumference to the radius of a circle. It is equal to two times pi (  2π ).

math.tau
#import the math library
import math

#print the value of Tau
print(math.tau)

#print the value of 2 times pi
print(2 * math.pi)