split py into modules

lektor_groupby/util.py

@@ -0,0 +1,11 @@
+from lektor.reporter import reporter, style
+
+
+def report_config_error(key: str, field: str, val: str, e: Exception) -> None:
+    ''' Send error message to Lektor reporter. Indicate which field is bad. '''
+    msg = '[ERROR] invalid config for [{}.{}] = "{}",  Error: {}'.format(
+        key, field, val, repr(e))
+    try:
+        reporter._write_line(style(msg, fg='red'))
+    except Exception:
+        print(msg)  # fallback in case Lektor API changes