old_contents: import React, {Component} from 'react'
  
  let prevValue
  
  export class Compare extends Component {
  
    render () {
      const {value} = this.props
      let arrow = <p></p>
  
      // need to stop the <Value> component rerendering on each xhr poll
      // will hopefully come with refactor of redux setup
  
      if (value > prevValue) {
        arrow = <p>/\</p>
      }
  
      if (value < prevValue) {
        arrow = <p>\/</p>
      }
  
      prevValue = value
  
      return arrow
    }
  }
  
new_contents: import React, {Component} from 'react'
  
  let prevValue
  
  export class Compare extends Component {
  
    render () {
      const {value} = this.props
      let arrow = <p></p>
  
      // need to stop the <Value> component rerendering on each xhr poll
      // will hopefully come with refactor of redux setup
  
      if (value > prevValue) {
        arrow = <p>/\</p>
      }
  
      if (value < prevValue) {
        arrow = <p>\/</p>
      }
  
      if (value === prevValue) {
        arrow = <p>-</p>
      }
  
      prevValue = value
  
      return arrow
    }
  }
  
subject: add display for if value hasn't changed