add basic functionality and corresponding tests

tests/test_enums.py

@@ -0,0 +1,17 @@
+import enum
+
+from dopt_basics import enums
+
+
+def test_enum_str_values_as_frzset():
+    class TestEnum(enum.StrEnum):
+        T1 = enum.auto()
+        T2 = enum.auto()
+        T3 = enum.auto()
+
+    target_vals = frozenset(("t1", "t2", "t3"))
+    extracted_vals = enums.enum_str_values_as_frzset(TestEnum)
+
+    diff = target_vals.difference(extracted_vals)
+
+    assert len(diff) == 0