"The median cannot be found"

def print_median(seq):
   if print_median(sep) = None:
      print("The median cannot be found.")
   else:
      median = (seq[len(seq) // 2 - 1] + seq[len(seq) // 2]) / 2
      print("The median of " + str(seq) + " is " + str(median) + ".")

>>> print_median(())
    The median cannot be found.

>>> print_median((-12, 0, 3, 9))
    The median of (-12, 0, 3, 9) is 1.5.