input: def calculate_distance(x1: float, y1: float, x2: float, y2: float) -> float:
      """ Calculate and return the distance between two points (x1, y1) and (x2, y2)
      on a two-dimensional plane.
      
      Example:
      >>> calculate_distance(3.0, 4.0, -9.0, -2.0)
      13.601470508735444
      """
output:     return ((x2 - x1) ** 2 + (y2 - y1) ** 2) ** 0.5