socket module now exports all the needed constants used for
socket operations, such as SO_BROADCAST.
popen() and fdopen() in the os
module now follow the pattern of the built-in function open():
the default mode argument is 'r' and the optional third
argument specifies the buffer size, where 0 means unbuffered,
1 means line-buffered, and any larger number means the size of
the buffer in bytes.