Description

BitString returns the set as a string of 1s and 0s denoting the sum of the i'th powers of 2, for each i in s. A radix point, always preceded by a digit, appears if the sum is non-integral.

Examples:

        {}.BitString() =      "0"
     {4,5}.BitString() = "110000"
      {-3}.BitString() =      "0.001"
{-3,0,4,5}.BitString() = "110001.001"