input: Write a function to filter selected items from a list of dictionaries.
  assert select_data([{'selected': True, 'value': 1}, {'selected': False, 'value': 2}, {'selected': True, 'value': 3}]) == [{'selected': True, 'value': 1}, {'selected': True, 'value': 3}]
  assert select_data([{'selected': False, 'value': 1}, {'selected': False, 'value': 2}]) == []
  assert select_data([{'selected': True, 'value': 5}, {'selected': True, 'value': 7}, {'selected': False, 'value': 9}]) == [{'selected': True, 'value': 5}, {'selected': True, 'value': 7}]
output: def select_data(items):
      return [item for item in items if item['selected']]