#!/usr/bin/env python2
# -*- coding: utf-8 -*-

import math


def is_numeric(lista):
    bool = False
    for i in lista:
        bool = isinstance(i, int) or isinstance(i, float)
        if not bool:
            return False
    return bool

print(is_numeric([-1,2.1,3]))

print(is_numeric([-1,2.1, '3',3]))

print(is_numeric(['2']))

print(is_numeric([None]))