Implement beta_ratio.from_scipy

yli/distributions.py

@@ -28,6 +28,10 @@ class betarat_gen(stats.rv_continuous):
 	2. Weekend Editor. On the ratio of Beta-distributed random variables. Some Weekend Reading. 2021 Sep 13. https://www.someweekendreading.blog/beta-ratios/
 	"""
 	
+	def from_scipy(self, beta1, beta2):
+		"""Construct a new beta_ratio distribution from two SciPy beta distributions"""
+		return self(*beta1.args, *beta2.args)
+	
 	def _do_vectorized(self, func, x, a1, b1, a2, b2):
 		"""Helper function to call the implementation over potentially multiple values"""