docs: function handleEntryPoint ( index, value, that ) {
  
          var percentage;
  
          // Wrap numerical input in an array.
          if ( typeof value === "number" ) {
              value = [value];
          }
  
          // Reject any invalid input, by testing whether value is an array.
          if ( Object.prototype.toString.call( value ) !== '[object Array]' ){
              throw new Error("noUiSlider: 'range' contains invalid value.");
          }
  
          // Covert min/max syntax to 0 and 100.
          if ( index === 'min' ) {
              percentage = 0;
          } else if ( index === 'max' ) {
              percentage = 100;
          } else {
              percentage = parseFloat( index );
          }
  
          // Check for correct input.
          if ( !isNumeric( percentage ) || !isNumeric( value[0] ) ) {
              throw new Error("noUiSlider: 'range' value isn't numeric.");
          }
  
          // Store values.
          that.xPct.push( percentage );
          that.xVal.push( value[0] );
  
          // NaN will evaluate to false too, but to keep
          // logging clear, set step explicitly. Make sure
          // not to override the 'step' setting with false.
          if ( !percentage ) {
              if ( !isNaN( value[1] ) ) {
                  that.xSteps[0] = value[1];
              }
          } else {
              that.xSteps.push( isNaN(value[1]) ? false : value[1] );
          }
  
          that.xHighestCompleteStep.push(0);
      }