Why is only the parameter `attention_mask` singular?
In Transformers library, why is only the parameterattention_masksingular? Evenhead_maskis singular too.I am asking this because other parameters likeinput_ids,position_idsandlabelsare plural in forward().Is there any historical reason for that choice?One hypothesis I think is that for one sample in a batch,attention_maskcorresponds to one andinput_idscorresponds to multiple values.However, this does not explain whylabelsis plural.