fix lint

calculator/operators.py

 """
 Operator module contains the Operator class and a list of standard operators.
 """
+
+
 class Operator:
     """
     Operator class is a binary operator with a symbol, a precedence and an evaluation function.
     """
+
     def __init__(self, symbol, precedence, evaluate_function):
         self.symbol = symbol
         self.precedence = precedence
@@ -17,4 +20,5 @@ class Operator:
         return self.evaluate_function(left, right)
 
 
-STANDARD_OPERATORS = { '+': Operator('+', 1, lambda a, b: a + b),'-': Operator('-', 1, lambda a, b: a - b),'*': Operator('×', 2, lambda a, b: a * b),'/': Operator('/', 2, lambda a, b: a / b)}
+STANDARD_OPERATORS = {'+': Operator('+', 1, lambda a, b: a + b), '-': Operator('-', 1, lambda a,
+    b: a - b), '*': Operator('×', 2, lambda a, b: a * b), '/': Operator('/', 2, lambda a, b: a / b)}