StompFrame and StompHeartBeat __str__ method returns bytes in Python 3

[larserikh]

The __str__ method must return a string in Python 3 but for StompFrame and StompHeartBeat it returns bytes. For example:

from stompest.protocol import StompFrame, StompSpec
frame = StompFrame(StompSpec.SEND, rawHeaders=[('foo', 'bar1'), ('foo', 'bar2')])
bytes(frame)
b'SEND\nfoo:bar1\nfoo:bar2\n\n\x00'
str(frame)
Traceback (most recent call last):
File "", line 1, in
TypeError: str returned non-string (type bytes)

Maybe __str__ should just call info()?