def startswith_(a, fragment, msg=None):
    'Assert a.startswith(fragment), with repr messaging on failure.'
    assert a.startswith(fragment), (msg or ('%r does not start with %r' % (a, fragment)))
Assert a.startswith(fragment), with repr messaging on failure.
def startswith_(a, fragment, msg=None):
    
    assert a.startswith(fragment), (msg or ('%r does not start with %r' % (a, fragment)))