code: def is_suburi(self, base, test):
          
          if base == test:
              return True
          if base[0] != test[0]:
              return False
          common = posixpath.commonprefix((base[1], test[1]))
          if len(common) == len(base[1]):
              return True
          return False
docs: Check if test is below base in a URI tree
  
          Both args must be URIs in reduced form.