pretraining objective of T5 model 
# 🚀 Feature request

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Hi, it would be great to have pretraining of T5 model implemented. Currently, run_mlm.py script does not support it.

## Motivation

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T5 is the SOTA model and having pertaining would be very helpful to the community.


This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

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