input: 
  def delete_key(dic, k):
      """
      Delete a given key from a dictionary.
      >>> delete_key({'foo': 1, 'bar': 2, 'baz': 3}, 'baz')
      {'foo': 1, 'bar': 2}
      >>> delete_key({'a': 10, 'b': 20, 'c': 30}, 'd')
      {'a': 10, 'b': 20, 'c': 30}
      """
      if k in dic:
          del dic[k]
          return dic
      return dic
  
output:     
      if k in dic:
          del dic[k]
          return dic
      return dic
  