nano_) must be either 1
or 3. If you don't care which your address is, you can use * as the first character
which will be twice as fast by ignoring the result of the first character.
1, 3,
or either via *. Please see the note above.
is not a valid character in a Nano address.
Nano addresses can be composed of the numbers and lowercase, except
0, 2, l, and v.
*).