trac 28582 fix doctest

fchapoton · fchapoton · commit 6694a513ab8b · 2019-10-09T11:11:39.000+02:00
diff --git a/src/doc/en/thematic_tutorials/coercion_and_categories.rst b/src/doc/en/thematic_tutorials/coercion_and_categories.rst
@@ -155,7 +155,6 @@ This base class provides a lot more methods than a general parent::
      'is_integrally_closed',
      'is_noetherian',
      'is_prime_field',
-     'is_ring',
      'is_subring',
      'krull_dimension',
      'ngens',
