I have a topology that covers a big area. I cannot validate all at once 'cause I get errors. So I've created a grid that covers the area. 
Through a script runned from my .mxd I intend to:
1. itterate through each grid cell
2. set it as the current extent of the map, 
3. use the tool "Validate Topology", having checked the option "VISIBLE\_EXTENT".

The workflow sounds correct to me, but I'm blocked at the first two steps. Here's my code:

```
import arcpy
mxd = arcpy.mapping.MapDocument("CURRENT")
df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]
gridLayer = arcpy.mapping.ListLayers(mxd, "Caroiaj_RO", df)[0] 

# Create SearchCursor
with arcpy.da.SearchCursor(gridLayer, ("GridName2")) as cursor:

# Start a loop that iterates through all rows 
    for row in cursor:

    # Clause to select only the current record
        whereClause = ' "GridName2" = ' + str(row.GridName2)

        # Select Layer by attribute
        arcpy.SelectLayerByAttribute_management(gridLayer, "NEW_SELECTION", whereClause)

        df.extent = gridLayer.getSelectedExtent(True)

        arcpy.RefreshActiveView()

del cursor, row
del mxd 

```

Thanx a lot!