[Tkinter] output "os" in frame

[m_clayton]

I tried this way:

import subprocess

def lsblk():
    records = subprocess.Popen('/usr/bin/lsblk', shell=True).readlines()

in this way, I display the output in bash.
I'm returning this error:

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python3.6/tkinter/__init__.py", line 1702, in __call__
    return self.func(*args)
  File "os.py", line 20, in lsblk
    records  =subprocess.Popen('/usr/bin/lsblk').readlines()
AttributeError: 'Popen' object has no attribute 'readlines'

my version python 3.6 and 2.7
I use as os arch linux