code: function() { 
              var l = this.coeffs.length;
              while(l--) {
                  var c = this.coeffs[l];
                  var equalsZero = c.equals(0);
                  if(c && equalsZero) {
                      if(l === 0) break;
                      this.coeffs.pop();
                  }
                  else break;
              }
  
              return this;
          }
docs: Removes higher order zeros or a specific coefficient
  @returns {Array}