# pty.py -- Pseudo terminal utilities.
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- select(rlist, wlist, xlist[, timeout]) -> (rlist, wlist, xlist)
- Wait until one or more file descriptors are ready for some kind of I/O.
- The first three arguments are lists of file descriptors to be waited for:
- rlist -- wait until ready for reading
- wlist -- wait until ready for writing
- xlist -- wait for an ``exceptional condition''
- If only one kind of condition is required, pass  for the other lists.
- A file descriptor is either a socket or file object, or a small integer
- gotten from a fileno() method call on one of those.
- The optional 4th argument specifies a timeout in seconds; it may be
- a floating point number to specify fractions of seconds. If it is absent
- or None, the call will never time out.
- The return value is a tuple of three lists corresponding to the first three
- arguments; each contains the subset of the corresponding file descriptors
- that are ready.
- *** IMPORTANT NOTICE ***
- On Windows, only sockets are supported; on Unix, all file descriptors.
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CHILD = 0
STDERR_FILENO = 2
STDIN_FILENO = 0
STDOUT_FILENO = 1