code: def merge_stylesheets(Class, fn, *cssfns):
          
          stylesheet = Class(fn=fn)
          for cssfn in cssfns:
              css = Class(fn=cssfn)
              for sel in sorted(css.styles.keys()):
                  if sel not in stylesheet.styles:
                      stylesheet.styles[sel] = css.styles[sel]
                  else: 
                      for prop in [prop for prop in css.styles[sel] if prop not in stylesheet.styles[sel]]:
                          stylesheet.styles[sel][prop] = css.styles[sel][prop]
          return stylesheet
docs: merge the given CSS files, in order, into a single stylesheet. First listed takes priority.