The Mermaid printer in pyreverse incorrectly renders Python dunder methods and attributes. Double underscores (__) are output directly to Mermaid, which interprets them as Markdown bold formatting (**text**) instead of literal underscores.

This can be observed in the functional test files

The file contains entries like:

class P {
  name : str
  __init__(name: str)
}
class SpecialAttr {
  __x__
  __init__()
}

When viewed in a Mermaid renderer, __init__ and __x__ display as bold text instead of showing the literal underscores.

Command used:

pyreverse -o mmd --filter-mode=ALL tests/pyreverse/functional/class_diagrams/aggregation_filtering/all.py

Pylint output:
The generated .mmd file contains unescaped double underscores that render incorrectly in Mermaid viewers.

Expected behavior:
Double underscores in method and attribute names should render as literal underscores in Mermaid diagrams, not as bold formatting.

Pylint version:

pylint 4.0.0-dev0
astroid 4.0.0a0
Python 3.13.2 (main, Feb 12 2025, 14:49:53) [MSC v.1942 64 bit (AMD64)]