Unbuffer stopped working months ago

I find the "unbuffer" command very important and useful, because I am running python code, and I don't think I can just put something equivalent to fflush() everywhere.

I used to use it just fine: unbuffer python foo.py | tee filename.log

A few months ago, I'm not sure if I had allowed my Ubuntu 16.04 to auto update some software, and it stopped working.

$ unbuffer
can't find package Expect
    while executing
"package require Expect"
    (file "/usr/bin/unbuffer" line 6)

I tried editing some files and changing Expect to lower case expect but it didn't work.

I tried (months ago) using apt-get tools to uninstall and reinstall Expect, but to no avail. I'm surprised I can't google this and find others complaining about it not working.

I just tried it on a friend's 18.04 Ubuntu. He has never used it, he downloaded it with apt-get and gets the same failure message. Any help appreciated.

Thanks @pynexj for the suggestion to cat /usr/bin/unbuffer:

#!/bin/sh
# -*- tcl -*-
# The next line is executed by /bin/sh, but not tcl \
exec tclsh8.6 "$0" ${1+"$@"}

package require expect


# -*- tcl -*-
# Description: unbuffer stdout of a program
# Author: Don Libes, NIST

if {[string compare [lindex $argv 0] "-p"] == 0} {
    # pipeline
    set stty_init "-echo"
    eval [list spawn -noecho] [lrange $argv 1 end]
    close_on_eof -i $user_spawn_id 0
    interact {
    eof {
        # flush remaining output from child
        expect -timeout 1 -re .+
        return
    }
    }
} else {
    set stty_init "-opost"
    set timeout -1
    eval [list spawn -noecho] $argv
    expect
    exit [lindex [wait] 3]
}

I have been using conda on this machine, but I'm running these tests in a terminal where I have not done any source activate. The first item in my path is /home/myusername/anaconda3/bin , if that matters.

$ apt list --installed | grep -i expect

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

expect/xenial,now 5.45-7 amd64 [installed]
python3-pexpect/xenial,xenial,now 4.0.1-1 all [installed]
tcl-expect/xenial,now 5.45-7 amd64 [installed,automatic]

$ locate '*expect*pkgIndex.tcl'
/usr/lib/tcltk/x86_64-linux-gnu/expect5.45/pkgIndex.tcl

Thanks @glenn jackman, I found that my tclsh is in ~/anaconda3/bin/tclsh and points to tclsh8.6 I guess this means it was installed as part of my conda installation. As noted above, anaconda3/bin is at the top of my PATH. I haven't built anything myself.

Do we know if 8.6 is old or new? Should I try to do a apt-get update on tcl or tclsh, outside of conda stuff, and see if that helps?