Optimize yer CSS through Python

cssoptimize.py

def optimize_css(directory):
    import os
    from csscompressor import compress
    print("\tOptimizing CSS in " + directory)
    file_paths = []  # List which will store all of the full filepaths.
    # Walk the tree.
    for root, directories, files in os.walk(directory):
        for filename in files:
            # Join the two strings in order to form the full filepath.
            filepath = os.path.join(root, filename)
            file_paths.append(filepath)  # Add it to the list.
    # Now we have a list of all CSS files in directory.
    for source in file_paths:
        if source[-4:] == ".css" and source[-8:-4] != "-min":   # if we have a CSS file and it's not already minimized ...
            with open(source, "r") as sourcefilehandle:
                rawcss = sourcefilehandle.read()
            target = source[:-4] + "-min.css"   # New ending to the filename
            with open(target, "w") as targetfilehandle:
                targetfilehandle.write(compress(rawcss))
    return