input: Write a Python function to determine the highest cumulative value from a series 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(tuples):
      aggregate = {}
      for name, value in tuples:
          if name not in aggregate:
              aggregate[name] = value
          else:
              aggregate[name] += value
      max_name = max(aggregate, key=aggregate.get)
      return (max_name, aggregate[max_name])