Update symbolic_expression.py

pep8 and import cleanup

Author: fchapoton

src/sage/tests/memcheck/symbolic_expression.py

@@ -2,11 +2,10 @@
 
 
 def test_sqrt_sqrt_2() -> None:
-    from sage.all import sqrt
+    from sage.misc.functional import sqrt
     T2 = sqrt(2)
-    
+
     def sqrt_T2() -> None:
         sqrt(T2)
-        
-    verify_no_leak(sqrt_T2)
 
+    verify_no_leak(sqrt_T2)