input: Write a function to calculate the maximum aggregate from the list of tuples.
  assert max_aggregate([('Juan Whelan',90),('Sabah Colley',88),('Peter Nichols',7),('Juan Whelan',122),('Sabah Colley',84)])==('Juan Whelan', 212)
  assert max_aggregate([('Juan Whelan',50),('Sabah Colley',48),('Peter Nichols',37),('Juan Whelan',22),('Sabah Colley',14)])==('Juan Whelan', 72)
  assert max_aggregate([('Juan Whelan',10),('Sabah Colley',20),('Peter Nichols',30),('Juan Whelan',40),('Sabah Colley',50)])==('Sabah Colley', 70)
  
output: def max_aggregate(lst):
      agg = {}
      for name, score in lst:
          if name in agg:
              agg[name] += score
          else:
              agg[name] = score
      max_name = max(agg, key=agg.get)
      return (max_name, agg[max_name])