diff --git a/elementpath/datatypes.py b/elementpath/datatypes.py
index e954ddc..99b4ad0 100644
--- a/elementpath/datatypes.py
+++ b/elementpath/datatypes.py
@@ -1114,7 +1114,7 @@ class ArithmeticTypeProxy(object):
     @staticmethod
     def instance_check(other):
         return isinstance(other, (int, float, decimal.Decimal, AbstractDateTime, Duration)) \
-               and not isinstance(other, bool)
+            and not isinstance(other, bool)
 
     @staticmethod
     def subclass_check(subclass):
diff --git a/elementpath/xpath_nodes.py b/elementpath/xpath_nodes.py
index 1663a5c..f159bb9 100644
--- a/elementpath/xpath_nodes.py
+++ b/elementpath/xpath_nodes.py
@@ -235,30 +235,3 @@ def node_string_value(obj):
     elif is_processing_instruction_node(obj):
         return obj.text
 
-
-###
-# XPath base functions
-def boolean_value(obj, token=None):
-    """
-    The effective boolean value, as computed by fn:boolean().
-    Moved to token class but kept for backward compatibility.
-    """
-    if isinstance(obj, list):
-        if not obj:
-            return False
-        elif isinstance(obj[0], tuple) or is_element_node(obj[0]):
-            return True
-        elif len(obj) == 1:
-            return bool(obj[0])
-        else:
-            raise xpath_error(
-                code='FORG0006', token=token, prefix=getattr(token, 'error_prefix', 'err'),
-                message="Effective boolean value is not defined for a sequence of two or "
-                "more items not starting with an XPath node.",
-            )
-    elif isinstance(obj, tuple) or is_element_node(obj):
-        raise xpath_error(
-            code='FORG0006', token=token, prefix=getattr(token, 'error_prefix', 'err'),
-            message="Effective boolean value is not defined for {}.".format(obj)
-        )
-    return bool(obj)
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 059fbf2..b80a180 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -22,6 +22,7 @@ from elementpath.xpath_nodes import AttributeNode, NamespaceNode, is_etree_eleme
     is_namespace_node, is_processing_instruction_node, is_text_node, node_attributes, \
     node_base_uri, node_document_uri, node_children, node_is_id, node_is_idrefs, \
     node_nilled, node_kind, node_name, node_string_value
+from elementpath.xpath_helpers import boolean_value
 from elementpath.xpath1_parser import XPath1Parser
 
 
@@ -245,5 +246,23 @@ class NodeHelpersTest(unittest.TestCase):
         self.assertIsNone(node_string_value(10))
 
 
+class CompatibilityHelpersTest(unittest.TestCase):
+
+    def test_boolean_value_function(self):
+        elem = ElementTree.Element('A')
+
+        self.assertFalse(boolean_value([]))
+        self.assertTrue(boolean_value([elem]))
+        self.assertFalse(boolean_value([0]))
+        self.assertTrue(boolean_value([1]))
+        with self.assertRaises(TypeError):
+            boolean_value([1, 1])
+        with self.assertRaises(TypeError):
+            boolean_value(elem)
+        self.assertFalse(boolean_value(0))
+        self.assertTrue(boolean_value(1))
+
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/tests/test_schema_proxy.py b/tests/test_schema_proxy.py
index ec3d308..14698c3 100644
--- a/tests/test_schema_proxy.py
+++ b/tests/test_schema_proxy.py
@@ -114,6 +114,10 @@ class XPath2ParserXMLSchemaTest(test_xpath2_parser.XPath2ParserTest):
         facet_type = schema_proxy.get_type('{%s}facet' % XSD_NAMESPACE)
         any_type = schema_proxy.get_type('{%s}anyType' % XSD_NAMESPACE)
         self.assertEqual(schema_proxy.get_primitive_type(facet_type), any_type)
+        self.assertEqual(schema_proxy.get_primitive_type(any_type), any_type)
+
+        any_simple_type = schema_proxy.get_type('{%s}anySimpleType' % XSD_NAMESPACE)
+        self.assertEqual(schema_proxy.get_primitive_type(any_simple_type), any_simple_type)
 
     def test_is_instance_api(self):
         self.assertFalse(self.schema_proxy.is_instance(True, '{%s}integer' % XSD_NAMESPACE))