Support for decoding of TDNN-LSTM nnet3?

vosk api is defautly support for decoding of TDNN nnet3.
I did some experiments, the TDNN-LSTM is obviously better than TDNN and the TDNN-LSTM get 3% gain comparing with TDNN.
The TDNN-LSTM needs the parameter as follows:
`extra_left_context=0
extra_right_context=0
extra_left_context_initial=-1
extra_right_context_final=-1
`
but i can not find these parameters in src codes.