/**
* Returns the (minimum) length of a number expressed in bits.
*
* @param a
* @returns The bit length
*/
export function bitLength (a: number|bigint): number {
if (typeof a === 'number') a = BigInt(a)
if (a === 1n) { return 1 }
let bits = 1
do {
bits++
} while ((a >>= 1n) > 1n)
return bits
}