Revert "Create special _find() function"

This reverts commit 5e708ff.

Author: bouwew

plugwise/helper.py

@@ -63,7 +63,6 @@
     InvalidAuthentication,
     InvalidXMLError,
     ResponseError,
-    XMLDataMissingError,
 )
 from .util import (
     escape_illegal_xml_characters,
@@ -73,17 +72,6 @@
 )
 
 
-def _find(xml_in: etree, locator: str) -> list[str]:
-    """Helper-function for use of etree.find()."""
-    if xml_in is not None:
-        if (found := xml_in.find(locator)) is not None:
-            return found
-
-        return None
-
-    raise XMLDataMissingError()
-
-
 def update_helper(
     data: DeviceDataPoints,
     devices: dict[str, DeviceData],