code: function(a, epsilon) {
              if(epsilon == undefined) epsilon = EPSILON;
              let allSignsFlipped = false;
              if (e.length != a.length)
                  expected(e, "to have the same length as", a);
                  
              for (let i = 0; i < e.length; i++) {
                  if (isNaN(e[i]) !== isNaN(a[i]))
                      expected(e, "to be equalish to", a);
                  
                  if (allSignsFlipped) {
                      if (Math.abs(e[i] - (-a[i])) >= epsilon)
                          expected(e, "to be equalish to", a);
                  } else {
                      if (Math.abs(e[i] - a[i]) >= epsilon) {
                          allSignsFlipped = true;
                          i = 0;
                      }
                  }
              }
          }
docs: Dual quaternions are very special & unique snowflakes