def _traverse_and_find(module_name, directory):
    """
    Traverse a directory (recursively), and look for a file named 
    'module_name'.by.

    Args:
        module_name (str):              Module to look for.
        directory (str):                Path to directory to traverse.

    Returns:
        str: Full path of bython file associated with module, None if no such
        file is found.
    """
    for rootpath, subdirs, files in os.walk(directory):
        for file in files:
            if file == (module_name+".by"):
                return os.path.join(rootpath, file)

    return None

    Traverse a directory (recursively), and look for a file named 
    'module_name'.by.

    Args:
        module_name (str):              Module to look for.
        directory (str):                Path to directory to traverse.

    Returns:
        str: Full path of bython file associated with module, None if no such
        file is found.
    
bython/importing.py