function displayNums (n) {
  let html = '<ul>/n'
  let color
  for (let i = 0; i <= n; i++) {
    if (i % 2 === 0) {
      color = 'blue'
      html += ` <li><span style='color:
      ${color}'>${i}</span></li>\n`
      console.log(html)
    } else {
      color = 'green'
      html += ` <li><span style='color:
      ${color}'>${i}</span></li>\n`
      console.log(html)
    }
  }
}
displayNums(10)