Function to get CartoCSS from Python dicts

def cssify(css_dict):
    """Function to get CartoCSS from Python dicts"""
    css = ''
    for key, value in dict_items(css_dict):
        css += '{key} {{ '.format(key=key)
        for field, field_value in dict_items(value):
            css += ' {field}: {field_value};'.format(field=field,
                                                     field_value=field_value)
        css += '} '
    return css.strip()