Docs (#81)

* clean `condition` module
* add docs

pina/model/multi_feed_forward.py

@@ -6,16 +6,17 @@ from .feed_forward import FeedForward
 
 class MultiFeedForward(torch.nn.Module):
     """
+    This model allows to create a network with multiple FeedForward combined
+    together. The user has to define the `forward` method choosing how to
+    combine the different FeedForward networks.
+
     :param dict dff_dict: dictionary of FeedForward networks.
     """
-    def __init__(self, dff_dict):
-        '''
-        dff_dict: dict of FeedForward objects
-        '''
+    def __init__(self, ffn_dict):
         super().__init__()
 
-        if not isinstance(dff_dict, dict):
+        if not isinstance(ffn_dict, dict):
             raise TypeError
 
-        for name, constructor_args in dff_dict.items():
+        for name, constructor_args in ffn_dict.items():
             setattr(self, name, FeedForward(**constructor_args))