
[;1m  byte_size(Bitstring)[0m

  Returns an integer that is the number of bytes needed to contain [;;4m[0m
  [;;4mBitstring[0m. That is, if the number of bits in [;;4mBitstring[0m is not
  divisible by 8, the resulting number of bytes is rounded up.

  For example:

    > byte_size(<<433:16,3:3>>).
    3
    > byte_size(<<1,2,3>>).
    3
