Correct “an” → “a” with “Unicode”, “user”, “UTF”, etc

This affects documentation, code comments, and a debugging messages.
diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index 3ad0e99..964ae62 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -520,7 +520,7 @@
         return key;
     }
     else {
-        /* for other types, use the object identifier as an unique identifier
+        /* for other types, use the object identifier as a unique identifier
          * to ensure that they are seen as unequal. */
         PyObject *obj_id = PyLong_FromVoidPtr(op);
         if (obj_id == NULL)
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 230125b..b146da9 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -675,7 +675,7 @@
 }
 
 #ifdef Py_DEBUG
-/* Fill the data of an Unicode string with invalid characters to detect bugs
+/* Fill the data of a Unicode string with invalid characters to detect bugs
    earlier.
 
    _PyUnicode_CheckConsistency(str, 1) detects invalid characters, at least for