Formatting

* Adding black as dev dependency
* Formatting pina code
* Formatting tests

pina/loss/loss_interface.py

@@ -1,4 +1,4 @@
-""" Module for Loss Interface """
+"""Module for Loss Interface"""
 
 from abc import ABCMeta, abstractmethod
 from torch.nn.modules.loss import _Loss
@@ -58,4 +58,4 @@ class LossInterface(_Loss, metaclass=ABCMeta):
             ret = torch.sum(loss, keepdim=True, dim=-1)
         else:
             raise ValueError(self.reduction + " is not valid")
-        return ret
+        return ret