vendor/google.golang.org/appengine/internal/main_common.go - voltctl - Gitiles

 package internal

 // MainPath stores the file path of the main package. On App Engine Standard
 // using Go version 1.9 and below, this will be unset. On App Engine Flex and
 // App Engine Standard second-gen (Go 1.11 and above), this will be the
 // filepath to package main.
 var MainPath string
	package internal

	// MainPath stores the file path of the main package. On App Engine Standard
	// using Go version 1.9 and below, this will be unset. On App Engine Flex and
	// App Engine Standard second-gen (Go 1.11 and above), this will be the
	// filepath to package main.
	var MainPath string