Add Seriatim input module skeleton

internal/modules/input/seriatim/metadata.go

@@ -0,0 +1,28 @@
+package seriatim
+
+import (
+	"encoding/json"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+)
+
+const (
+	MetadataSpeaker = "speaker"
+	MetadataStart   = "start"
+	MetadataEnd     = "end"
+)
+
+func Speaker(unit source.SourceUnit) (string, bool) {
+	value, ok := unit.Metadata[MetadataSpeaker].(string)
+	return value, ok
+}
+
+func Start(unit source.SourceUnit) (json.Number, bool) {
+	value, ok := unit.Metadata[MetadataStart].(json.Number)
+	return value, ok
+}
+
+func End(unit source.SourceUnit) (json.Number, bool) {
+	value, ok := unit.Metadata[MetadataEnd].(json.Number)
+	return value, ok
+}