How to feed a file as stdin to a Jupyter Notebook Python script?

Question

Hello!
I'm studying at Coursera and I'm writing my scripts in Jupyter Notebook. For submission, Coursera requires the scripts to read from stdin and write to stdout. This is easily done on command line, for example: python script.py < input.txt
However, during the coding phase (ie in Jupyter), I would like to read this - say - input.txt for the script. I can't figure out how to do such redirect in Jupyter Notebook. There is just a run button, no command line argument field or anything.
Any ideas?

Answer 1

I didn't see a direct answer but these hints may get you there. For example, you can read from a docstring as if it were a file (called a "here" doc), and I've done redirection and 'inside' reading in several codes.
First, Jupyter magic methods (shells, external cmds, etc)
% lsmagic
To suggest in the area of redirecting stdin:
Redirect stdout (capture 'import this' / StringIO)
https://code.sololearn.com/cV31QM0B0ozB/?ref=app
Redirect stderr/stdout (symbol encoding)
https://code.sololearn.com/c6NQFsmNHz82/?ref=app
module "io" variables as streams (BytesIO here):
https://docs.python.org/3.5/library/io.html
https://code.sololearn.com/cpl25LvQ3wvu/?ref=app
StringIO, bash-like "here" doc for data input:
https://stackoverflow.com/questions/45414616/bash-like-heredoc-for-data-input