Compute the running median of a sequence of numbers. That is, given a stream of numbers, print out the median of the list so far on each new element. Recall that the median of an even-numbered list is the average of the two middle numbers.

Example:

>>> coding_problem_33([2, 1, 5, 7, 2, 0, 5])
[2, 1.5, 2, 3.5, 2, 2.0, 2]