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 <a href="https://gis.stackexchange.com/questions/108655/raster-to-polygon-conversion">link</a> 
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 "<string>",
> line 18, in <module> 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)