code: function(x) {
              x = Number(x) || 0;
              var l = this.coeffs.length;
              for(var i=0; i<l; i++) {
                  if(this.coeffs[i] === undefined) { this.coeffs[i] = new Frac(x); }
              }
              return this;
          }
docs: Fills in the holes in a polynomial with zeroes
  @param {Number} x - The number to fill the holes with