var (// MainFileValidExtension is the extension that must be used for files in new sketchesMainFileValidExtension = ".ino"// MainFileValidExtensions lists valid extensions for a sketch fileMainFileValidExtensions = map[string]bool{MainFileValidExtension:true,".pde":true,}// AdditionalFileValidExtensions lists any file extension the builder considers as validAdditionalFileValidExtensions = map[string]bool{".h":true,".c":true,".hpp":true,".hh":true,".cpp":true,".cxx":true,".cc":true,".S":true,".adoc":true,".md":true,".json":true,".tpp":true,".ipp":true,}// SourceFilesValidExtensions lists valid extensions for source files (no headers).// If a platform do not provide a compile recipe for a specific file extension, this// map provides the equivalent extension to use as a fallback.SourceFilesValidExtensions = map[string]string{".c":   "",".cpp": "",".cxx": ".cpp",".cc":  ".cpp",".S":   "",}// HeaderFilesValidExtensions lists valid extensions for header filesHeaderFilesValidExtensions = map[string]bool{".h":true,".hpp":true,".hh":true,}// DefaultIndexURL is the default index urlDefaultIndexURL = "https://downloads.arduino.cc/packages/package_index.tar.bz2"// LibrariesIndexURL is the URL where to get the libraries index.LibrariesIndexURL, _ =url.Parse("https://downloads.arduino.cc/libraries/library_index.tar.bz2")// LibrariesIndexResource is the IndexResource to get the libraries index.LibrariesIndexResource =resources.IndexResource{URL:LibrariesIndexURL,EnforceSignatureVerification:true,})