input: Write a Python function to sort a list of tuples based on their float values.
  assert float_sort([('item1', '12.20'), ('item2', '15.10'), ('item3', '24.5')])==[('item3', '24.5'), ('item2', '15.10'), ('item1', '12.20')] 
  assert float_sort([('item1', '15'), ('item2', '10'), ('item3', '20')])==[('item3', '20'), ('item1', '15'), ('item2', '10')] 
  assert float_sort([('item1', '5'), ('item2', '10'), ('item3', '14')])==[('item3', '14'), ('item2', '10'), ('item1', '5')]
output: def float_sort(lst):
      return sorted(lst, key=lambda x: float(x[1]), reverse=True)