How to create local copy of Sockets to get at source to determine code path for error codes

The intent is to convert an error code to an error message.
All errors return Unknown System Error

DNSError:, Unknown system error 2 (Unknown system error 2)

I tried “dev” but I got this error:
(@v1.9) pkg> dev Sockets

ERROR: The following package names could not be resolved:

  • Sockets (6462fe0b-24de-5631-8697-dd941f90decc in manifest but not in project)

Many standard libraries, including Sockets, live in the JuliaLang/julia repository, so cloning that repo gives you Sockets too, see stdlib/Sockets.

Thank you!