code: function (symbol) {
          if (Array.isArray(symbol)) {
              for (var i = 0; i < symbol.length; i++) {
                  this.disableTexture(symbol[i]);
              }
              return;
          }
  
          var status = this._textureStatus[symbol];
          if (status) {
              var isDisabled = ! status.enabled;
              if (!isDisabled) {
                  status.enabled = false;
                  this._programKey = '';
              }
          }
      }
docs: Disable a texture, it remove a #define macro in the shader
  @param  {string} symbol