#4572: add SEEK_* values as constants in io.py.

Doc/library/io.rst

@@ -265,12 +265,18 @@ I/O Base Classes
       interpreted relative to the position indicated by *whence*.  Values for
       *whence* are:
 
-      * ``0`` -- start of the stream (the default); *offset* should be zero or positive
-      * ``1`` -- current stream position; *offset* may be negative
-      * ``2`` -- end of the stream; *offset* is usually negative
+      * :data:`SEEK_SET` or ``0`` -- start of the stream (the default);
+        *offset* should be zero or positive
+      * :data:`SEEK_CUR` or ``1`` -- current stream position; *offset* may
+        be negative
+      * :data:`SEEK_END` or ``2`` -- end of the stream; *offset* is usually
+        negative
 
       Return the new absolute position.
 
+      .. versionadded:: 2.7
+         The ``SEEK_*`` constants
+
    .. method:: seekable()
 
       Return ``True`` if the stream supports random access.  If ``False``,

Lib/io.py

@@ -66,6 +66,11 @@ import threading
 # open() uses st_blksize whenever we can
 DEFAULT_BUFFER_SIZE = 8 * 1024  # bytes
 
+# for seek()
+SEEK_SET = 0
+SEEK_CUR = 1
+SEEK_END = 2
+
 # py3k has only new style classes
 __metaclass__ = type