'Count the trailing zeroes'

def _op_generic_Ctz(self, args):

    wtf_expr = claripy.BVV(self._from_size, self._from_size)
    for a in reversed(range(self._from_size)):
        bit = claripy.Extract(a, a, args[0])
        wtf_expr = claripy.If((bit == 1), claripy.BVV(a, self._from_size), wtf_expr)
    return wtf_expr
