add missing file

Author: bernt-matthias

planemo/linters/util.py

@@ -0,0 +1,16 @@
+from typing import (
+    Optional,
+    TYPE_CHECKING,
+)
+
+if TYPE_CHECKING:
+    from galaxy.tool_util.parser.interface import ToolSource
+    from galaxy.util import Element
+
+
+def xml_node_from_toolsource(tool_source: "ToolSource", tag: "str") -> Optional["Element"]:
+    node = None
+    xml_tree = getattr(tool_source, "xml_tree", None)
+    if xml_tree:
+        node = xml_tree.find(tag)
+    return node