Non-blocking connect

[mp]

Code is at bottom. Basically, if I turn off socket blocking prior to
connecting, I get a "Socket is not connected" error when I try to send
data. However, if I do not turn off blocking, OR if I place a print
statement anywhere before the send call, it works! WTF?

I'd like to understand what's going on in the background here, if you
know don't skimp on the details.

Thanks

---------------------------------------------------------------
import
socket
sock = socket.socket(socket.AF_INET,
socket.SOCK_STREAM)
sock.setblocking(0)
sock.connect_ex(('localhost',
9000))
sock.setblocking(1)
sock.send('foo')
sock.close()