Revert "use hmm for ipe model" (#208)

Reverts #207

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Co-authored-by: Xiaoyan Wang <[email protected]>
Co-authored-by: georgematheos <[email protected]>
Co-authored-by: nishadgothoskar <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Karen Chung <[email protected]>