├── __init__.py
├── metadata.txt
├── pluginMain.py
├── plugin_ui.py
├── plugin_ui.ui
├── resources.qrc
├── resources_rc.py
├── sub
│   ├── __init__.py
│   └── qcf.py
├── ui.py

import sub.qcf
print sub.qcf

File "/Users/.../.qgis2/python/plugins/.../ui.py", line 26, in
    print sub.qcf
AttributeError: 'module' object has no attribute 'qcf'

Python 2.7.11 (default, Dec  7 2015, 12:36:04)
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.72)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sub.qcf
>>> print sub.qcf
<module 'sub.qcf' from 'sub/qcf.pyc'>