Hi @j0pgrm, re #81

Your `if` statement is there to cover the possbility that your PRNG will generate the number 1. 
In general, PRNGs produce values from 0 to _less than_ 1, i.e. from the range 0 (inclusive) to 1 (exclusive). This is because when they generate an N-bit binary fraction, the highest value (all `1`s) will be just a tiny bit smaller than 1.

Your `Math.floor` correctly rounds downward, so that `rand` will be in the range 0 (inclusive) to ENCODING_LEN *- 1* (inclusive). 
So the `if` will never be triggered.

If, for some reason, you in future switch to a prng that somehow can generate a 1, for example because it has an idiosyncratic desire to cover a range of 0 (_exclusive_) to 1 (_inclusive_), then:

* the chance of this is extremely small (1 in 2**N, not 1 in 2**8)
* the PRNG will have lost the ability to generate 0
* your random character generator would have a micrscopically smaller chance of generating the first encoding character, and have a microscopic chance of trying to pick the non-existent character at #ENCODING_LEN.

A neat solution for you is to simply wrap round that exactly-1 PRNG value back to 0, most conveniently  A simple way to achieve this is to modulo the `rand` by ENCODING_LEN.



Thank you for an excellent library.

Resolve #81 to deal with a potential future scenario of PRNG generating `1`