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iMac27:~ apple$ brew --cellar wireguard-tools
ERROR: Your version of macOS (10.13.6) is too old to run Homebrew!
         For 10.5 - 10.13.6 support see: https://www.macports.org

ERROR: Your version of macOS (10.13.6) is too old to run Homebrew!
         For 10.5 - 10.13.6 support see: https://www.macports.org

==> Downloading https://ghcr.io/v2/homebrew/core/portable-ruby/blobs/sha256:f2bc4c3b081b09d7dcca97a8b8c5e102116e6ba68a5c118d6d961cf33b3162ec
Already downloaded: /Users/apple/Library/Caches/Homebrew/portable-ruby-4.0.3.catalina.bottle.tar.gz
==> Pouring portable-ruby-4.0.3.catalina.bottle.tar.gz
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/./4.0.3/bin/ruby (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/./4.0.3/bin/ruby (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

/usr/local/Homebrew/Library/Homebrew/cmd/vendor-install.sh: line 257:  7911 Abort trap: 6           "./${VENDOR_VERSION}/bin/${VENDOR_NAME}" --version > /dev/null
Error: Failed to install ruby 4.0.3!
Error: Failed to upgrade Homebrew Portable Ruby!
iMac27:~ apple$