make return values more explicit

lib/galaxy/tool_util/loader_directory.py

@@ -198,31 +198,32 @@ def as_dict_if_looks_like_yaml_or_cwl_with_class(path, classes):
         try:
             start_contents = f.read(5 * 1024)
         except UnicodeDecodeError:
-            return None
+            return False, None
         if re.search(rf"\nclass:\s+({'|'.join(classes)})\s*\n", start_contents) is None:
-            return None
+            return False, None
 
     with open(path) as f:
         try:
             as_dict = yaml.safe_load(f)
         except Exception:
-            return None
+            return False, None
 
     if not isinstance(as_dict, dict):
-        return None
+        return False, None
 
     file_class = as_dict.get("class", None)
     if file_class not in classes:
-        return None
+        return False, None
 
-    return as_dict
+    return True, as_dict
 
 
 def is_a_yaml_with_class(path, classes):
     """Determine if a file is a valid YAML with a supplied ``class`` entry."""
     if not _has_extension(path, YAML_EXTENSIONS):
         return False
-    return as_dict_if_looks_like_yaml_or_cwl_with_class(path, classes) is not None
+    is_yaml, as_dict = as_dict_if_looks_like_yaml_or_cwl_with_class(path, classes)
+    return is_yaml
 
 
 def looks_like_a_tool_yaml(path):
@@ -235,8 +236,8 @@ def looks_like_a_cwl_artifact(path, classes=None):
     if not _has_extension(path, CWL_EXTENSIONS):
         return False
 
-    as_dict = as_dict_if_looks_like_yaml_or_cwl_with_class(path, classes)
-    if as_dict is None:
+    is_yaml, as_dict = as_dict_if_looks_like_yaml_or_cwl_with_class(path, classes)
+    if not is_yaml is None:
         return False
 
     file_cwl_version = as_dict.get("cwlVersion", None)