gistfile1.py

import os
import imp

_commands = []

files = [f for f in os.listdir('.') if os.path.isfile(f)]
for f in files:
    filename, extention = os.path.splitext(f)
    if filename[0:4] == '_cmd_' and extention == '.py':
        module = imp.load_source(filename, '.')
        if hasattr(modle, 'CommandClass'):
            _commands.append(getattr(py_mod, expected_class)())