Make sure that the program allows one or both of the files to be specified with filename substitution characters

Modify mycp to prompt for arguments if none are supplied. A typical execution of the modified version should look like this:
$ mycp
Source file name? voucher
Destination file name? voucher.sv
$

The only change required is to replace the arg number check conditional block with the following:
if [ "$#" -ne 2 ] ; then
echo "Source file name? \c" ; read from
echo "Destination file name? \c" ; read to
else
from="$1"
to="$2"
fi
Otherwise the program remains identical.