add rasch functionality to form generation

app/lib/irt/item_information_function.py

@@ -1,6 +1,7 @@
 import logging
 
 from lib.irt.models.three_parameter_logistic import ThreeParameterLogistic
+from lib.irt.models.rasch import Rasch
 from lib.errors.item_generation_error import ItemGenerationError
 
 
@@ -20,6 +21,10 @@ class ItemInformationFunction():
                 return (self.model_data.a_param * q *
                         (p - self.model_data.c_param)**2) / (p * (
                             (1 - self.model_data.c_param)**2))
+            elif self.model_data.model == 'RASCH':
+                p = Rasch(self.model_data, kwargs).result()
+                q = 1 - p
+                return p * q
             else:
                 # potentially error out
                 raise ItemGenerationError(