This issue is supposed to track when we can start to use typing_extensions.Self (PEP 673) in typeshed. Support is needed in released versions of:

• PEP accepted
• mypy (Add support for Self type mypy#14041)
• pytype
• pyright (Implement proposed "Self" type microsoft/pyright#2515)
• pyre
• PyCharm (nice to have, but not required)