bug or feature: open and io.open are not interchangeable
<p>I always thought open and io.open were interchangeable.<br>
Apparently not, if i believe this snippet:</p>

<pre><code>import ctypes, io

class POINT(ctypes.Structure):
    _fields_ = [("x", ctypes.c_int),("y", ctypes.c_int)]
# THIS WORKS
with open("mypoints.bin", "wb") as f: 
    for i in range(10):
        p = POINT(i,10-i)
        print p.x, p.y
        f.write(p)
# THIS FAILS 
with io.open("mypoints.bin", "wb") as f:
    for i in range(10):
        p = POINT(i,10-i)
        print p.x, p.y
        f.write(p)

0 10
Traceback (most recent call last):
  File "D:\test.py", line 10, in &lt;module&gt;
    f.write(p)
  File "c:\Python26\lib\io.py", line 1070, in write
    self._write_buf.extend(b)
TypeError: 'POINT' object is not iterable
</code></pre>

<p>EDIT: i use python 2.6.6</p>
