code: def _css_min(src, dest='', preserve_comments=True):
      
  
      if dest == '': # all default
          return _css_min_exec(_text(src))
      else:
          if type(dest) is bool:  #dest is skept, custom pattern provided at dist place
              return _css_min_exec(_text(src), dest)
          else:
              with open(dest, 'w') as f2:
                  return f2.write(_css_min_exec(_text(src), preserve_comments))
docs: Minify CSS
  
      Args:
          src: css string or path-to-file with text to beautify (mandatory)
          dest: path-to-file to save beautified css string; if file doesn't exist
                it is created automatically; (optional)
                if this arg is skept function returns string
          preserve_comments: if set False, all comments are removed from minified text
                             default is True (comments are preserved)
  
      Returns: 1) minified CSS string if dest is not provided
               2) length of saved file if dest is provided
  
      Example:
              css.min('path/to/file.css')
              css.min('path/to/file.css', 'path/to/save/result.css')
              css.min('path/to/file.css', False)
              css.min('path/to/file.css', 'path/to/save/result.css', False)