coercion tutorial: Update some examples...

...to reflect that Rings gained a few parent methods

Author: mezzarobba

src/doc/en/thematic_tutorials/coercion_and_categories.rst

@@ -105,27 +105,24 @@ it makes sense to build on top of the base class
 This base class provides a lot more methods than a general parent::
 
     sage: [p for p in dir(Field) if p not in dir(Parent)]
-    ['__div__', '__fraction_field', '__ideal_monoid', '__iter__',
-     '__pow__', '__rdiv__', '__rpow__', '__rxor__', '__xor__',
-     '_an_element', '_an_element_c', '_an_element_impl', '_coerce_',
-     '_coerce_c', '_coerce_impl', '_coerce_self', '_coerce_try',
-     '_default_category', '_gens', '_gens_dict',
-     '_has_coerce_map_from', '_ideal_class_', '_latex_names', '_list',
-     '_one_element', '_pseudo_fraction_field',
-     '_random_nonzero_element', '_richcmp', '_unit_ideal',
-     '_zero_element', '_zero_ideal', 'algebraic_closure',
-     'base_extend', 'cardinality', 'class_group', 'coerce_map_from_c',
-     'coerce_map_from_impl', 'content', 'divides', 'extension',
-     'fraction_field', 'frobenius_endomorphism', 'gcd', 'gen', 'gens',
-     'get_action_c', 'get_action_impl', 'has_coerce_map_from_c',
-     'has_coerce_map_from_impl', 'ideal', 'ideal_monoid',
-     'integral_closure', 'is_commutative', 'is_field', 'is_finite',
-     'is_integral_domain', 'is_integrally_closed', 'is_noetherian',
-     'is_prime_field', 'is_ring', 'is_subring', 'is_zero',
-     'krull_dimension', 'list', 'ngens', 'one', 'one_element',
-     'order', 'prime_subfield', 'principal_ideal', 'quo', 'quotient',
-     'quotient_ring', 'random_element', 'unit_ideal', 'zero',
-     'zero_element', 'zero_ideal', 'zeta', 'zeta_order']
+    ['__div__', '__fraction_field', '__ideal_monoid', '__iter__', '__pow__',
+    '__rdiv__', '__rpow__', '__rxor__', '__xor__', '_an_element',
+    '_an_element_c', '_an_element_impl', '_coerce_', '_coerce_c',
+    '_coerce_impl', '_coerce_self', '_coerce_try', '_default_category', '_gens',
+    '_gens_dict', '_has_coerce_map_from', '_ideal_class_', '_latex_names',
+    '_list', '_one_element', '_pseudo_fraction_field',
+    '_random_nonzero_element', '_richcmp', '_unit_ideal', '_zero_element',
+    '_zero_ideal', 'algebraic_closure', 'base_extend', 'cardinality',
+    'class_group', 'coerce_map_from_c', 'coerce_map_from_impl', 'content',
+    'divides', 'extension', 'fraction_field', 'frobenius_endomorphism', 'gcd',
+    'gen', 'gens', 'get_action_c', 'get_action_impl', 'has_coerce_map_from_c',
+    'has_coerce_map_from_impl', 'ideal', 'ideal_monoid', 'integral_closure',
+    'is_commutative', 'is_field', 'is_finite', 'is_integral_domain',
+    'is_integrally_closed', 'is_noetherian', 'is_prime_field', 'is_ring',
+    'is_subring', 'krull_dimension', 'list', 'ngens', 'one', 'one_element',
+    'order', 'prime_subfield', 'principal_ideal', 'quo', 'quotient',
+    'quotient_ring', 'random_element', 'unit_ideal', 'zero', 'zero_element',
+    'zero_ideal', 'zeta', 'zeta_order']
 
 The following is a very basic implementation of fraction fields, that needs to
 be complemented later.
@@ -404,9 +401,9 @@ coincide::
 
     sage: import inspect
     sage: len([s for s in dir(MS1) if inspect.ismethod(getattr(MS1,s,None))])
-    55
+    56
     sage: len([s for s in dir(MS2) if inspect.ismethod(getattr(MS2,s,None))])
-    78
+    80
     sage: MS1.__class__ is MS2.__class__
     True