code: function(state) {
              this.setState({
                  panels: this.state.panels.map(function(panel) {
                      panel.checked = state.index === panel.index
                      return panel
                  })
              })
          }
docs: /*
  onChange(state) {
  this.setState({
  panels: this.state.panels.map(panel => ({
  ...panel,
  checked: state.index === panel.index
  }))
  })
  }