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