import error for BPF on Ubuntu 16.04.7

Hi,

I am getting below error after installing all required packages.

`Python 2.7.12 (default, Mar 1 2021, 11:38:31)
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from bcc import BPF
Traceback (most recent call last):
File "", line 1, in
ImportError: cannot import name BPF`
Host System Information:

`Distributor ID: Ubuntu
Description: Ubuntu 16.04.7 LTS
Release: 16.04
Codename: xenial`

Start by reproducing `from bcc import BPF` with Python 2.7.12 on Ubuntu 16.04.7, then inspect the installed BCC package and its installation requirements. Compare the environment with the project's supported Ubuntu and Python versions; done when the cause is identified and the import succeeds or the unsupported setup is clearly documented.

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