message: lint DonutChart
diff: @@ -4,7 +4,7 @@ import PropTypes from 'prop-types'
  import {arc as Arc, pie as Pie} from 'd3-shape'
  function mapData(data) {
  - return Object.keys(data).map((key, i) => <DonutSlice key={key} state={key} value={data[key]} />)
  + return Object.keys(data).map(key => <DonutSlice key={key} state={key} value={data[key]} />)
  }
  const DonutChart = props => {
  @@ -16,14 +16,14 @@ const DonutChart = props => {
  const pie = Pie().value(child => child.props.value)
  // coerce the children into an array
  - const childList = React.Children.map(children, d => d)
  + const childList = React.Children.toArray(children)
  const arcData = pie(childList)
  const arc = Arc()
  .innerRadius(innerRadius)
  .outerRadius(radius)
  const slices = childList.map((child, i) => {
  - return <DonutSlice {...child.props} d={arc(arcData[i])} key={i} />
  + return <DonutSlice {...child.props} d={arc(arcData[i])} key={child.props.key} />
  })
  return (
  