However, I don't understand this entire point: What do you mean by
"using TCGETA requires that struct termio be defined"? How is TCGETA
defined to produce such a dependency? TCGETA is a constant, right?
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terminal I/O control has three different implementations under SVR4, 
BSD, and POSIX.1. 

SVR4 uses the termio structure, and various ioctl calls (such as 
TCGETA, TCSETA, TCSETAW, and TCSETAF) on a terminal device to obtain 
and set parameters with the termio structure.

Under POSIX, the termios struct is used, along with various functions 
defined by POSIX.1, such as tcsetattr and tcgetattr.

Under QNX
<termios.h> - is POSIX implimentation with functions tcsetattr and 
tcgetattr defined, but in <ioctl.h> that included in <termio.h> define 
MACROS TCGETA, TCSETA, TCSETAW, and TCSETAF.
That's why we need <termio.h> or simlink <sys/termio.h>.
Why do you want TCGETA, TCSETA, TCSETAW, and TCSETAF in Python if 
there is POSIX tcsetattr and tcgetattr functions?