code: function(connection, collection, from, to, options, cb) {
        return connections[connection].createEdge(from, to, options, cb);
      }
docs: /*
  Custom methods
  
  Custom methods defined here will be available on all models which
  are hooked up to this adapter
  
  e.g.: foo: function (collectionName, options, cb) {
  return cb(null,"ok"); }, bar: function
  (collectionName, options, cb) { if (!options.jello) return
  cb("Failure!"); else return cb(); destroy: function (connection,
  collection, options, values, cb) { return cb(); } // So if you have three
  models: // Tiger, Sparrow, and User // 2 of which (Tiger and Sparrow)
  implement this custom adapter, // then you'll be able to access: // //
  Tiger.foo(...) // Tiger.bar(...) // Sparrow.foo(...) // Sparrow.bar(...) //
  Example success usage: // // (notice how the first argument goes away:)
  Tiger.foo({}, function (err, result) { if (err) return
  console.error(err); else console.log(result); // outputs: ok }); //
  Example error usage: // // (notice how the first argument goes away:)
  Sparrow.bar({test: 'yes'}, function (err, result){ if (err)
  console.error(err); else console.log(result); // outputs: Failure! })
   
  Create Edge
  
  Creates edge between two vertices pointed by from and to
  
  @param {Object} connection
  @param {Object} collection
  @param {Object} from
  @param {Object} to
  @param {Object} options
  @param {Object} cb