small improvement based on go.tools
go get github.com/athom/go.tools/godoc/vfs/mapfs
This subrepository holds the source for various packages and tools that support the Go programming language. Some of the tools, godoc and vet for example, are included in binary Go distributions. Others, including the Go oracle and the test coverage tool, can be fetched with "go get". Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs. To submit changes to this repository, see http://golang.org/doc/contribute.html.