Update FC from CSV

# Joshua Tanner
# Loop through a CSV and Feature Class
# to update the fields
import csvkit, os

inCSV = "\\location\\of\\file"
data = {}
indexfield = "id"

reader = csvkit.py3.CSVKitDictReader(open(inCSV))
readerindex = reader.fieldnames.index(indexfield)
mxd = arcpy.mp.ArcGISProject('current')
map = mxd.listMaps()[0]
layer = map.listLayers()[0]

edit = arcpy.da.Editor(os.path.dirname(layer.dataSource))
edit.startEditing(False, True)

def updateRow(myrow):
    if(myrow[readerindex] is not None):
        reader = csvkit.py3.CSVKitDictReader(open(inCSV))
        for record in reader:
            if int(record[indexfield]) == int(myrow[readerindex]):
                for idx, field in enumerate(reader.fieldnames):
                    myrow[idx] = record[field]
    return myrow
                  

with arcpy.da.UpdateCursor(layer, reader.fieldnames) as cursor:
    for row in cursor:
        updatedrow = updateRow(row)
        cursor.updateRow(updatedrow)

edit.stopEditing(True)