Use a NumPy array containing a single integer $2,$ stored as an unsigned $64-$bit integer, to calculate $2$ raised to the $63$rd power minus $1.$ Then convert or print that value as a binary number which should have $63\text{'}1\text{'}$ characters in it$.$ This requires relatively little code, but you'll need to use NumPy's dtype, think carefully about the types of objects, and review or lookup ways to display a value as binary. No unit tests required.