input: Write a python function to calculate the area and circumference of a circle given its radius.
  assert calculate_circle(2) == (12.56, 12.56)
  assert calculate_circle(5) == (78.5, 31.400000000000002)
  assert calculate_circle(0) == (0.0, 0.0)
output: def calculate_circle(radius):
      pi = 3.14
      area = pi * radius * radius
      circumference = 2 * pi * radius
      return area, circumference