SVG.Doc = SVG.invent({
  // Initialize node
  create: function(node) {    
    this.constructor.call(this, node || SVG.create('svg'))

    // set svg element attributes and ensure defs node
    this.namespace().defs()
  }

  // Inherit from
, inherit: SVG.Container

  // Add class methods
, extend: {
    // Add namespaces
    namespace: function() {
      return this
        .attr({ xmlns: SVG.ns, version: '1.1' })
        .attr('xmlns:xlink', SVG.xlink, SVG.xmlns)
        .attr('xmlns:svgjs', SVG.svgjs, SVG.xmlns)
    }
    // Creates and returns defs element
  , defs: function() {
      return (this.node.getElementsByTagName('defs')[0] || this.put(new SVG.Defs).node).instance
    }
    // custom parent method
  , parent: function() {
      return this.node.parentNode.nodeName == '#document' ? null : this.node.parentNode
    }
      // Removes the doc from the DOM
  , remove: function() {
      if(this.parent()) {
        this.parent().removeChild(this.node)
      }

      return this
    }
  , clear: function() {
      // remove children
      while(this.node.hasChildNodes())
        this.node.removeChild(this.node.lastChild)
      return this
    }
  , toNested: function() {
      var el = SVG.create('svg')
      this.node.instance = null
      el.appendChild(this.node)

      return SVG.adopt(this.node)
    }
  }

})