Nested emphasises aren't processed

[dreamscached]

Unsure if this was already reported or is being worked on; please correct me if so.

The problem is the following:

>>> import mistune
>>> md = mistune.create_markdown()
>>> md('***foo**bar*')
'<p>***foo**bar*</p>\n' 

As you can see, an attempt to create nested emphasis leads to both being ignored; however, when using triple asterisks, it works as expected:

>>> md('***foobar***')
'<p><em><strong>foobar</strong></em></p>\n'

Mistune version is 3.0.0

I would first suppose it's my fault with custom renderer, but here I'm trying it on a fresh virtual environment with no plugins and built-in HTML renderer. I would also think it's probably maybe something nonstandard, but nearly every service that uses Markdown seems to work fine with this case.

P.S. Briefly looking into how it's made, maybe it's worth splitting logic and implement rather not by usage of special *** token but rather by recognizing it as * and ** located one inside the other and vice versa?