First implementation of an atom feed

extensionElement.go

@@ -0,0 +1,19 @@
+package atomfeed
+
+import (
+	"encoding/xml"
+	"errors"
+)
+
+type ExtensionElement struct {
+	Value   any `xml:",innerxml"`
+	XMLName xml.Name
+}
+
+func (e *ExtensionElement) Check() error {
+	if e.Value == nil {
+		return errors.New("value element of extension element empty")
+	}
+
+	return nil
+}