import os

IMG_EXTENSIONS = [
    '.jpg', '.JPG', '.jpeg', '.JPEG',
    '.png', '.PNG', '.ppm', '.PPM', '.bmp', '.BMP',
]

def is_image_file(filename):
    return any(filename.endswith(extension) for extension in IMG_EXTENSIONS)

def mkdirs(paths):
    """create empty directories if they don't exist
    Parameters:
        paths (str list) -- a list of directory paths
    """
    if isinstance(paths, list) and not isinstance(paths, str):
        for path in paths:
            make_dir(path)
    else:
        make_dir(paths)

def make_dir(target_dir):
    """
    Create dir if not exists
    """
    if not os.path.exists(target_dir):
        os.makedirs(target_dir)