calculates the median of a list of numbers

median.py

def median(numbers):
  sorted_numbers= sorted(numbers)
  size = len(sorted_numbers)
  median = 0
  if(size % 2 == 0):
    index_1 = size/2
    print index_1
    index_2 = index_1 -1
    print index_2
    sum =(sorted_numbers[index_1] + sorted_numbers[index_2]) 
    median = sum/ 2.0
  else:
    median = sorted_numbers[(size / 2)]
  return median

print median([4, 5,5,4])