# "TypeError: expected Line, got list" in Python. Why!

**URL:** <https://forum.dynamobim.com/t/typeerror-expected-line-got-list-in-python-why/24404>\
**Category:** Revit\
**Tags:** python\
**Created:** [August 2, 2018, 11:51am UTC](https://forum.dynamobim.com/t/typeerror-expected-line-got-list-in-python-why/24404 "2018-08-02T11:51:32Z")\
**Posts on this page:** 1\
**Showing post:** 6

<div class="post-metadata">

**Author:** ![Daniel\_Woodcock1](https://avatars.discourse-cdn.com/v4/letter/d/58f4c7/32.png) [@Daniel\_Woodcock1](https://forum.dynamobim.com/u/Daniel_Woodcock1)\
**Post date:** [August 2, 2018, 3:29pm UTC](https://forum.dynamobim.com/t/typeerror-expected-line-got-list-in-python-why/24404/6 "2018-08-02T15:29:05Z")

</div>

Yup, sorry… You need to make sure you create a reference array to store the references. Here is the full working code…

```
import clr

clr.AddReference("RevitServices")
import RevitServices
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager
doc = DocumentManager.Instance.CurrentDBDocument
app = DocumentManager.Instance.CurrentUIApplication.Application

clr.AddReference("RevitNodes")
import Revit
clr.ImportExtensions(Revit.Elements)
clr.ImportExtensions(Revit.GeometryConversion)

clr.AddReference("RevitAPI")
from Autodesk.Revit.DB import *

def tolist(obj1):
	if hasattr(obj1," __iter__"): return obj1
	else: return [obj1]

view = tolist(UnwrapElement(IN[0]))[0]
dimLines = tolist(UnwrapElement(IN[1]))
linesToDim = tolist(UnwrapElement(IN[2]))

refArrays = []

outList = []

for lineList in linesToDim:
	rArr = ReferenceArray()
	for l in lineList:
		rArr.Append(Reference(l))
	refArrays.append(rArr)

TransactionManager.Instance.EnsureInTransaction(doc)
for l,r in zip(dimLines,refArrays):
	try:
		outList.append(doc.Create.NewDimension(view,l.GeometryCurve,r))
	except Exception,e:
		outList.append(e.message)
	
TransactionManager.Instance.TransactionTaskDone()

OUT = outList

```

This should work for you. Easier now I have a pc with a monitor! 😄

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/f/4/f45195c127b2c2027ca4c96daba4473410b75560.png)

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