input: Write a function to calculate the distance between two points on a two-dimensional plane given their coordinates (x1, y1) and (x2, y2). The function should return the distance as a float.
  assert calculate_distance(3, 4, -9, -2) == 13.0
  assert calculate_distance(0, 0, 0, 0) == 0.0
  assert calculate_distance(1, 1, 4, 5) == 5.0
  assert calculate_distance(-3, -4, -3, -4) == 0.0
  assert calculate_distance(15, 20, -10, -8) == 34.84
output: def calculate_distance(x1, y1, x2, y2):
      return ((x2 - x1) ** 2 + (y2 - y1) ** 2) ** 0.5