Add notion of adding implicit parens before parsing the expression. This allows for newlines in the expressions.

pep-0498.txt

@@ -269,26 +269,21 @@ Is equivalent to::
   >>> 'result=' + str(foo())
   'result=20'
 
-After stripping leading and trailing whitespace (see below), the
+Expressions are parsed with the equivalent of ``ast.parse('(' +
-expression is parsed with the equivalent of ``ast.parse(expression,
+expression + ')', '<fstring>', 'eval')`` [#]_.
-'<fstring>', 'eval')`` [#]_. Note that this restricts the expression:
+
-it cannot contain any newlines, for example::
+Note that since the expression is enclosed by implicit parentheses
+before evaluation, expressions can contain newlines. For example::
 
   >>> x = 0
   >>> f'''{x
   ... +1}'''
-    File "<fstring>", line 2
+  '1'
-      +1
-      ^
-  SyntaxError: invalid syntax
 
-But note that this works, since the newline is removed from the
+  >>> d = {0: 'zero'}
-string, and the spaces in front of the ``'1'`` are allowed in an
+  >>> f'''{d[0
-expression::
+  ... ]}'''
-
+  'zero'
-  >>> f'{x+\
-  ...    1}'
-  '2'
 
 Format specifiers
 -----------------
@@ -374,7 +369,7 @@ or::
     File "<stdin>", line 2, in <module>
   ValueError: Sign not allowed in string format specifier
 
-Leading and trailing whitespace in expressions is skipped
+Leading and trailing whitespace in expressions is ignored
 ---------------------------------------------------------
 
 For ease of readability, leading and trailing whitespace in