% cd /tmp
% mkdir testmod
% cd testmod
% go mod -init -module example.com/example
go: creating new go.mod: module example.com/example
% echo 'package example; import _ "gopkg.in/yaml.v2"' > example.go
% go build
% go mod -graph -json
{
	"Module": {
		"Path": "example.com/example"
	},
	"Require": [
		{
			"Path": "gopkg.in/yaml.v2",
			"Version": "v2.2.1"
		}
	],
	"Exclude": null,
	"Replace": null
}
example.com/example gopkg.in/yaml.v2@v2.2.1
gopkg.in/yaml.v2@v2.2.1 gopkg.in/check.v1@v0.0.0-20161208181325-20d25e280405