input: Write a function to calculate the distance between two points on a two-dimensional plane. The function should take in four parameters: x1, y1, x2, and y2, representing the coordinates of the two points. The function should return the distance as a float.
  def calculate_distance(x1, y1, x2, y2):
      distance = ((x2 - x1)**2 + (y2 - y1)**2)**0.5
      return distance
  
  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(-1, -1, 1, 1) == 2.8284271247461903
  assert calculate_distance(1, 2, 3, 4) == 2.8284271247461903
output: def calculate_distance(x1, y1, x2, y2):
      distance = ((x2 - x1)**2 + (y2 - y1)**2)**0.5
      return distance