>>> from zona_de_cerca import area_circumferencia

>>> a = area_circumferencia(1)
>>> round(a, 4)
3.1416
>>> a = area_circumferencia(12.45)
>>> round(a, 4)
486.9547
>>> a = area_circumferencia(0.09)
>>> round(a, 4)
0.0254
>>> a = area_circumferencia(7)
>>> round(a, 4)
153.938