set.pop() documentation is confusing

Objects/setobject.c

 
 /* set object implementation
    Written and maintained by Raymond D. Hettinger <python@rcn.com>
    Derived from Lib/sets.py and Objects/dictobject.c.
 
    Copyright (c) 2003-2008 Python Software Foundation.
    All rights reserved.
 */
 
 #include "Python.h"
@@ skipping 725 matching lines @@
     }
     key = entry->key;
     Py_INCREF(dummy);
     entry->key = dummy;
     so->used--;
     so->table[0].hash = i + 1;  /* next place to start */
     return key;
 }
 
 PyDoc_STRVAR(pop_doc, "Remove and return an arbitrary set element.\n\
+Note that the element is not selected randomly,\n\
+the exact algorithm is implementation-specific.\n\
 Raises KeyError if the set is empty.");
 
 static int
 set_traverse(PySetObject *so, visitproc visit, void *arg)
 {
     Py_ssize_t pos = 0;
     setentry *entry;
 
     while (set_next(so, &pos, &entry))
         Py_VISIT(entry->key);
@@ skipping 1775 matching lines @@
     Py_DECREF(f);
 
     Py_DECREF(elem);
     Py_DECREF(dup);
     Py_RETURN_TRUE;
 }
 
 #undef assertRaises
 
 #endif