old_contents: // xlink
  var xlinkNS = 'http://www.w3.org/1999/xlink'
  var xlinkRE = /^xlink:/
  
  module.exports = {
  
    priority: 850,
  
    update: function (value) {
      if (this.arg) {
        this.setAttr(this.arg, value)
      } else if (typeof value === 'object') {
        this.objectHandler(value)
      }
    },
  
    objectHandler: function (value) {
      // cache object attrs so that only changed attrs
      // are actually updated.
      var cache = this.cache || (this.cache = {})
      var attr, val
      for (attr in cache) {
        if (!(attr in value))
          this.setAttr(attr, null)
          delete cache[attr]
      }
      for (attr in value) {
        val = value[attr]
        if (val !== cache[attr]) {
          cache[attr] = val
          this.setAttr(attr, val)
        }
      }
    },
  
    setAttr: function (attr, value) {
      if (value || value === 0) {
        if (xlinkRE.test(attr)) {
          this.el.setAttributeNS(xlinkNS, attr, value)
        } else {
          this.el.setAttribute(attr, value)
        }
      } else {
        this.el.removeAttribute(attr)
      }
    }
  
  }
  
new_contents: // xlink
  var xlinkNS = 'http://www.w3.org/1999/xlink'
  var xlinkRE = /^xlink:/
  
  module.exports = {
  
    priority: 850,
  
    update: function (value) {
      if (this.arg) {
        this.setAttr(this.arg, value)
      } else if (typeof value === 'object') {
        this.objectHandler(value)
      }
    },
  
    objectHandler: function (value) {
      // cache object attrs so that only changed attrs
      // are actually updated.
      var cache = this.cache || (this.cache = {})
      var attr, val
      for (attr in cache) {
        if (!(attr in value)) {
          this.setAttr(attr, null)
          delete cache[attr]
        }
      }
      for (attr in value) {
        val = value[attr]
        if (val !== cache[attr]) {
          cache[attr] = val
          this.setAttr(attr, val)
        }
      }
    },
  
    setAttr: function (attr, value) {
      if (value || value === 0) {
        if (xlinkRE.test(attr)) {
          this.el.setAttributeNS(xlinkNS, attr, value)
        } else {
          this.el.setAttribute(attr, value)
        }
      } else {
        this.el.removeAttribute(attr)
      }
    }
  
  }
  
subject: fix braces