minigrep

grep (globally search a regular expression and print)

Commands that can be used

1. cargo run to poem.txt
2. CASE_INSENSITIVE=1 cargo run to poem.txt
3. cargo test
4. cargo run frog poem.txt
5. cargo run body poem.txt
6. cargo run monomorphization poem.txt
7. cargo run > output.txt
8. cargo run to poem.txt > output.txt