_init_paths.py

import os.path as osp
import sys

def add_path(path):
    if path not in sys.path:
        sys.path.insert(0, path)

father_dir = osp.dirname(osp.dirname(__file__))

# Add lib to PYTHONPATH
lib_path = osp.join(father_dir, 'src', 'lib')
add_path(lib_path)