Refactors build methods onto Context object

main.go

@@ -85,7 +85,8 @@ Flags:
 	defer output.Close()
 
 	buffer := bytes.NewBuffer([]byte{})
-	tree := rendering.Build(iface).AST()
+	context := rendering.NewContext()
+	tree := context.Build(iface).AST()
 
 	err = format.Node(buffer, token.NewFileSet(), tree)
 	if err != nil {
@@ -97,7 +98,7 @@ Flags:
 		stderr.Fatalf("could not determine output absolute path: %s", err)
 	}
 
-	result, err := imports.Process(outputPath, buffer.Bytes(), nil)
+	result, err := imports.Process(outputPath, buffer.Bytes(), &imports.Options{FormatOnly: false})
 	if err != nil {
 		stderr.Fatalf("could not process imports: %s\n\n%s", err, buffer.String())
 	}

parsing/argument.go

@@ -1,17 +1,28 @@
 package parsing
 
-import "go/types"
+import (
+	"go/types"
+)
 
 type Argument struct {
 	Name     string
 	Type     types.Type
 	Variadic bool
+	Package  string
 }
 
 func NewArgument(v *types.Var, variadic bool) Argument {
+	var pkg string
+	if t, ok := v.Type().(*types.Named); ok {
+		if t.Obj().Pkg() != nil {
+			pkg = t.Obj().Pkg().Path()
+		}
+	}
+
 	return Argument{
 		Name:     v.Name(),
 		Type:     v.Type(),
 		Variadic: variadic,
+		Package:  pkg,
 	}
 }