SVG.Parent = SVG.invent({
  // Initialize node
  create: function(element) {
    this.constructor.call(this, element)
  }

  // Inherit from
, inherit: SVG.Element

  // Add class methods
, extend: {
    // Returns all child elements
    children: function() {
      return this._children || (this._children = [])
    }
    // Add given element at a position
  , add: function(element, i) {
      if (!this.has(element)) {
        /* define insertion index if none given */
        i = i == null ? this.children().length : i
        
        /* remove references from previous parent */
        if (element.parent)
          element.parent.children().splice(element.parent.index(element), 1)
        
        /* add element references */
        this.children().splice(i, 0, element)
        this.node.insertBefore(element.node, this.node.childNodes[i] || null)
        element.parent = this
      }

      /* reposition defs */
      if (this._defs) {
        this.node.removeChild(this._defs.node)
        this.node.appendChild(this._defs.node)
      }
      
      return this
    }
    // Basically does the same as `add()` but returns the added element instead
  , put: function(element, i) {
      this.add(element, i)
      return element
    }
    // Checks if the given element is a child
  , has: function(element) {
      return this.index(element) >= 0
    }
    // Gets index of given element
  , index: function(element) {
      return this.children().indexOf(element)
    }
    // Get a element at the given index
  , get: function(i) {
      return this.children()[i]
    }
    // Get first child, skipping the defs node
  , first: function() {
      return this.children()[0]
    }
    // Get the last child
  , last: function() {
      return this.children()[this.children().length - 1]
    }
    // Iterates over all children and invokes a given block
  , each: function(block, deep) {
      var i, il
        , children = this.children()
      
      for (i = 0, il = children.length; i < il; i++) {
        if (children[i] instanceof SVG.Element)
          block.apply(children[i], [i, children])

        if (deep && (children[i] instanceof SVG.Container))
          children[i].each(block, deep)
      }
    
      return this
    }
    // Remove a child element at a position
  , removeElement: function(element) {
      this.children().splice(this.index(element), 1)
      this.node.removeChild(element.node)
      element.parent = null
      
      return this
    }
    // Remove all elements in this container
  , clear: function() {
      /* remove children */
      for (var i = this.children().length - 1; i >= 0; i--)
        this.removeElement(this.children()[i])

      /* remove defs node */
      if (this._defs)
        this._defs.clear()

      return this
    }
   , // Get defs
    defs: function() {
      return this.doc().defs()
    }
  }
  
})