Is it possible to make the separators in RecursiveCharacterTextSplitter support regular expressions?

[codeacme17]

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Feature request

Currently I am using RecursiveCharacterTextSplitter and hope to customize the splitting method when splitting markdown documents
(I do this in the python version:
https://github.com/codeacme17/examor/blob/66c6a0f993b64203c55e0c9c88360e63687f0d1b/server/loaders/markdown.py#L13).

But when I use js now, I find that the regular expression does not work. Is this because the segmentation method is to use includes method for strings?

Motivation

Please evaluate and I will submit pr if possible

Proposal (If applicable)

No response