Count the leading zeroes

def _op_generic_Clz(self, args):
        """Count the leading zeroes"""
        wtf_expr = claripy.BVV(self._from_size, self._from_size)
        for a in range(self._from_size):
            bit = claripy.Extract(a, a, args[0])
            wtf_expr = claripy.If(bit==1, claripy.BVV(self._from_size-a-1, self._from_size), wtf_expr)
        return wtf_expr