cat file0000.txt|./foo.py > out0000.txt

cat file00[0-4][0-9] |./foo.py > outfile1.txt &
cat file00[5-9][0-9] |./foo.py > outfile2.txt &
cat file01[0-4][0-9] |./foo.py > outfile3.txt &
cat file01[5-9][0-9] |./foo.py > outfile4.txt &