panic("invalid import path")
			}
			m.rename(&n.Path.Value)
			return false
		}
		return true
	})
}

// insertImportPath inserts the given import path.
// There must be at least one import declaration present already.
func insertImportPath(f *ast.File, path string) {
	for _, d := range f.Decls {
		if g, _ := d.(*ast.GenDecl); g != nil && g.Tok == token.IMPORT {