input: Write a python function to convert a list of tuples into a dictionary.
  assert list_to_dict([('a', 1), ('b', 2), ('c', 3)]) == {'a': 1, 'b': 2, 'c': 3}
  assert list_to_dict([('x', 10), ('y', 20), ('z', 30)]) == {'x': 10, 'y': 20, 'z': 30}
  assert list_to_dict([('key1', 'val1'), ('key2', 'val2')]) == {'key1': 'val1', 'key2': 'val2'}
output: def list_to_dict(lst):
      return dict(lst)