bash -- DSL for invoking subprocesses :: what you rather see in a code review: one-line shell pipeline or equivalent Python code? https://stackoverflow.com/questions/295459/how-do-i-use-subp... sh-like DSL on top of Python literal strings that doesn't invoke shell might be interesting (pep may help)

regex -- DSL for search/replace in text. Useful in moderation

jq -- DSL for search/replace in json. Useful on the command-line

xpath -- DSL for searching trees (hierarchy)

sql/xslt -- I would rather read Python most of the time instead but sometimes it is helpful to have an option of writing SQL directly (pep may help)

toml/json -- writing Python directly is preferable (in the context of .py file)

markdown -- DSL for writing markup (instead of html/word). I wouldn't say no to inline docstring rendering in Python code (pep may help). The same for (subset of) latex -- for math formulas `$e^{i \pi} -1 = 0$`

dot/plantuml (ebnf, sequence diagrams, etc) could be useful for literate programming-heavy style.