I'm trying to automate the conversion of raster to polygon and the raster files are in "TIF" format which is a "floating point". I copy the code below from this link so it needs some changes because of "unsigned integer" and ...that I don't know. how can I correct this code? I'm getting an error while executing it. Could you have some suggestions, please?

Runtime error Traceback (most recent call last): File "", line 18, in TypeError: 'NoneType' object is not iterable

Code

   `import arcpy, os
    ... from arcpy import env
    ... from arcpy.sa import *
    ... 
    ... #To overwrite output
    ... arcpy.env.overwriteOutput = True
    ... 
    ... #Set environment settings
    ... env.workspace = "K:\1400-10-20"
    ... 
    ... outws="K:\1400-10-20\m"
    ... 
    ... #checkout ArcGIS spatial analyst extension license
    ... arcpy.CheckOutExtension("Spatial")
    ... 
    ... inraster = arcpy.ListRasters("*", "TIF")
    ... 
    ... for i in inraster:
    ...     filename=os.path.splitext(i)[0]
    ...     outPolygons= outws + str(filename) + '.shape'
    ...     field = "VALUE"
    ...     arcpy.RasterToPolygon_conversion(i, outPolygons, "NO_SIMPLIFY", field)