Fix grammar

Doc/tutorial/errors.rst

@@ -184,7 +184,7 @@ attributes to it as desired. ::
    ... except Exception as inst:
    ...    print type(inst)     # the exception instance
    ...    print inst.args      # arguments stored in .args
-   ...    print inst           # __str__ allows args to printed directly
+   ...    print inst           # __str__ allows args to be printed directly
    ...    x, y = inst.args
    ...    print 'x =', x
    ...    print 'y =', y