Recently, CPython got a new syntax error, "SyntaxError: expression expected after dictionary key and ':'". I propose to add a "expected expression" in general for consistency. I would like to have it changed for all the "equals" (e.g. PLUSEQUAL, MINEQUAL, etc). 


>>> x =
  File "<stdin>", line 1
    x =
        ^
SyntaxError: invalid syntax

Would be enhanced by:

>>> x +=
  File "<stdin>", line 1
    x =
         ^
SyntaxError: expected expression