Clap: default value only if the flag was provides
./program --input 100 # set input to Some(100)
./program --input # set input to the dafult Some(42)
./program # input is None
## Exercise: implement accepting the parameters of wc
{id: exercise-command-line-of-wc}
You can get it either by typing "man wc" in your terminal or by visiting [man wc](https://linux.die.net/man/1/wc).
## Solution: implement accepting the parameters of wc
{id: solution-command-line-of-wc}
{i: TODO}
