input: Write a python function to create a class representing a Point in 2D space and calculate its distance from the origin.
  assert Point(3, 4).distance_from_origin() == 5.0
  assert Point(0, 0).distance_from_origin() == 0.0
  assert Point(1, 1).distance_from_origin() == 2**0.5
output: import math
  
  class Point:
      def __init__(self, x, y):
          self.x = x
          self.y = y
      
      def distance_from_origin(self):
          return math.sqrt(self.x**2 + self.y**2)