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python - Please explain this unexpected  (backspace) behavior

Expected:

>>> print "I print Backspace!"
I pri Backspa!
>>> print "I print Backspace!"
I pri Backsp!

Observed:

>>> print "I print Backspace!"
I pri Backspa!e
>>> print "I print Backspace!"
I pri Backsp!ce

Why does is 'e' and 'ce' not erased and '!' inserted?

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You didn't erase them; you merely backspaced. Going forward will overwrite the previous characters, but backspace doesn't erase as it backs up. You would want

print "I print Backspace  !"

... to see ...

I pri Backspa  !

If you want the "full effect", you have to backspace and overwrite wtih spaces as you back up ... then you can move forward. Something like

print "Backspace" + 2*" " + "!"

You can use the multiplier as many times as you wish; it's a small motif. The above line displays

Backspa!

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