input: Write a python function to perform basic operations (set, get, delete) on a dictionary.
  assert set_value({}, 'a', 1) == {'a': 1}
  assert get_value({'a': 1}, 'a') == 1
  assert delete_value({'a': 1}, 'a') == {}
output: def set_value(d, key, value):
      d[key] = value
      return d
  
  def get_value(d, key):
      return d.get(key)
  
  def delete_value(d, key):
      if key in d:
          del d[key]
      return d