def in_(a, b, msg=None):
    'Assert a in b, with repr messaging on failure.'
    assert (a in b), (msg or ('%r not in %r' % (a, b)))
Assert a in b, with repr messaging on failure.
def in_(a, b, msg=None):
    
    assert (a in b), (msg or ('%r not in %r' % (a, b)))