Code simplification.

Thanks @victor-torres for the suggestion

scrapy/utils/reqser.py

@@ -71,23 +71,19 @@ def request_from_dict(d, spider=None):
 
 
 def _find_method(obj, func):
-    if obj:
-        try:
-            func.__func__
-        except AttributeError:  # func is not a instance method. Not supported.
-            pass
-        else:
-            members = inspect.getmembers(obj, predicate=inspect.ismethod)
-            for name, obj_func in members:
-                # We need to use __func__ to access the original
-                # function object because instance method objects
-                # are generated each time attribute is retrieved from
-                # instance.
-                #
-                # Reference: The standard type hierarchy
-                # https://docs.python.org/3/reference/datamodel.html
-                if obj_func.__func__ is func.__func__:
-                    return name
+    # Only instance methods contain ``__func__``
+    if obj and hasattr(func, '__func__'):
+        members = inspect.getmembers(obj, predicate=inspect.ismethod)
+        for name, obj_func in members:
+            # We need to use __func__ to access the original
+            # function object because instance method objects
+            # are generated each time attribute is retrieved from
+            # instance.
+            #
+            # Reference: The standard type hierarchy
+            # https://docs.python.org/3/reference/datamodel.html
+            if obj_func.__func__ is func.__func__:
+                return name
     raise ValueError("Function %s is not an instance method in: %s" % (func, obj))