doc (miscellaneous.md): add example for sparql query (from unittest)

# Last 3 commits:

# f96456a I42 update 
# 91ae143 abstract pow / neg class 
# dd995a5 abstract add / mul class

docs/source/howto/miscellaneous.md

@@ -66,3 +66,27 @@ to type. Solutions:
     - The extension uses the entries in this file to offer auto-complete suggestions when the `erk-fzf.search` command is triggered (either via the VS code command pallette or via a manually assigned keyboard shortcut (recommended, see [README.md](https://github.com/ackrep-org/irk-fzf/blob/main/README.md)).
     - The command `erk-fzf.search` performs a fuzzy search using the string left of the cursor (and then the user input).
     It displays fuzzy-matching lines from `.ac_candidates.txt`. It searches short_keys, labels and descriptions.
+
+
+## How to perform a SPARQL query
+
+
+Example from `test_core.py:Test_04_Core.test_c020__sparql_query2`
+
+```python
+
+import pyirk as p
+p.ds.rdfgraph = p.rdfstack.create_rdf_triples()
+
+qsrc = f"""
+PREFIX : <{p.rdfstack.IRK_URI}>
+PREFIX ct: <{mod1.__URI__}#>
+SELECT ?s ?o
+WHERE {{
+    ?s :R16 ct:I7864.
+}}
+"""
+res = p.ds.rdfgraph.query(qsrc)
+res2 = p.aux.apply_func_to_table_cells(p.rdfstack.convert_from_rdf_to_pyirk, res)
+
+```

tests/test_core.py

@@ -1900,13 +1900,13 @@ def test_b02m__multilingual_relations2(self):
             self.assertEqual(I1001.R77__has_alternative_label, expected_result)
 
 
-class Test_Z_Core(HousekeeperMixin, unittest.TestCase):
+class Test_04_Core(HousekeeperMixin, unittest.TestCase):
     """
     Collection of test that should be executed last (because they seem to influence other tests).
     This is achieved by putting "ZZ" in the name (assuming that test classes are executed in alphabetical order).
     """
 
-    def test_sparql_query(self):
+    def test_c010_sparql_query(self):
         # This test seems somehow to influence later tests
         mod1 = p.irkloader.load_mod_from_path(TEST_DATA_PATH2, TEST_MOD_NAME)
         p.ds.rdfgraph = p.rdfstack.create_rdf_triples()
@@ -1921,7 +1921,7 @@ def test_sparql_query(self):
         ]
         self.assertEqual(res2[:2], expected_result)
 
-    def test_c01__sparql_query2(self):
+    def test_c020__sparql_query2(self):
         # TODO: replace by Model entity once it exists
         mod1 = p.irkloader.load_mod_from_path(TEST_DATA_PATH2, TEST_MOD_NAME)
 
@@ -1951,7 +1951,7 @@ def test_c01__sparql_query2(self):
         ]
         self.assertEqual(res2, expected_result)
 
-    def test_c02__sparql_zz_preprocessing(self):
+    def test_c030__sparql_zz_preprocessing(self):
         mod1 = p.irkloader.load_mod_from_path(TEST_DATA_PATH2, TEST_MOD_NAME)
 
         with p.uri_context(uri=TEST_BASE_URI):