arcgis 10.0 - How to edit (particularly flip direction of) polyline obtained through UpdateCursor?

I want to flip the direction of a polyline feature obtained as a result of an Update query; e.g.

lines= arcpy.UpdateCursor(myFeatureClass,myQuery)
dsc= arcpy.Describe(myFeatureClass)
try:
    for ln in lines:
        # ? Check number of parts

        # ? Flip direction of each, or some of the parts
        lines.updateRow(ln)
except:
    print "Error:", sys.exc_info()[0]
finally:
    # releasing locks
    if lines: del lines
    if ln: del ln

BTW, any better way to know how many rows are returned than counting them?

Answer

Just for the record, and to help the folks who might be looking:

def flipLine(myFeatureClass, myQuery):
    try:
        lines=arcpy.UpdateCursor(myFeatureClass, myQuery)
        dsc=arcpy.Describe(myFeatureClass)
        lc=0
        for ln in lines:
            if ln.shape.partCount > 1: 
                print "Warning: multiple parts! extra parts are automatically trimmed!"

            lp= ln.shape.getPart(0)
            rPnts=arcpy.Array()
            for i in range(len(lp)): rPnts.append(lp[len(lp)-i-1])
            rPoly=arcpy.Polyline(rPnts)
            ln.shape= rPoly
            lines.updateRow(ln)
    except:
        print "Error:", sys.exc_info()[0]
    finally:
        if lines: del lines

        if ln: del ln