Added missing grading.py file

book/examples/example_gumbel.py

@@ -1,4 +1,4 @@
-#from grading import check
+from grading import check
 from math import isclose
 
 tolerance = 0.001

book/examples/grading.py

@@ -0,0 +1,16 @@
+from IPython.display import display
+import ipywidgets as widgets
+
+def check(f):
+	def wrapper(*args, **kwargs):
+		output = widgets.Output()
+		button = widgets.Button(description="Check Answer(s)")
+		@output.capture(clear_output=True,wait=True)
+		def _inner_check(button):
+			try:	
+				f(*args, **kwargs)
+			except:
+				print("Something went wrong, have you filled all the functions and run the cells?")
+		button.on_click(_inner_check)
+		display(button, output)
+	return wrapper