input: 
  def calculate_distance(x1: float, y1: float, x2: float, y2: float) -> float:
      """ Calculates the Euclidean distance between two points on a two-dimensional plane.
      >>> calculate_distance(3, 4, -9, -2)
      13.0
      """
  
output:     return ((x2 - x1) ** 2 + (y2 - y1) ** 2) ** 0.5