take care of case when "_tied_weights_keys" is not an attribute (#3226)
* take care of case when "_tied_weights_keys" is not an attribute
Signed-off-by: Yu Chin Fabian Lim <flim@sg.ibm.com>
* fix style
Signed-off-by: Yu Chin Fabian Lim <flim@sg.ibm.com>
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Signed-off-by: Yu Chin Fabian Lim <flim@sg.ibm.com>