NOTE: This node has been removed from Rhythm. More info here:
Use this python as a replacement:
import clr
clr.AddReference("RevitNodes")
import Revit
clr.ImportExtensions(Revit.Elements)
clr.AddReference("RevitAPIUI")
from Autodesk.Revit.UI import *
clr.AddReference("RevitServices")
import RevitServices
from RevitServices.Persistence import DocumentManager
doc = DocumentManager.Instance.CurrentDBDocument
uidoc=DocumentManager.Instance.CurrentUIApplication.ActiveUIDocument
#offer the user the selection
elementReferences = uidoc.Selection.PickObjects(Selection.ObjectType.Element, 'Pick model elements')
#our list to append selection results to
elements = []
#obtain the elements via the id
for i in elementReferences:
try:
elements.append(doc.GetElement(i.ElementId))
except:
elements.append([])
OUT = elements
Pick Model Elements
Dynamo Hierarchy: Rhythm>Revit>Selection>Pick Model Elements
Description:
This node offers a pick method for selecting elements in Revit.
Inputs:
refresh : bool
Outputs:
elements : Element
Dynamo Nodes 
hi how do you input those code? i tried the python script and paste it all the exact same, but nothing happens,