I am used to \llceil and \rrceil from stmaryrd. An example of these delimiters in use is: https://i.stack.imgur.com/yJ0f7.jpg
Are these delimiters available through unicode-math or, more generally, in Unicode?
The best approximations I found via shapecatcher.com are ╓ and ╖, which, unfortunately, are unsuitable in their raw form as proper math ceiling-like delimiters.
Math & Science ⇒ \llceil, \rrceil in Unicode?
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