input: 
  def delete_key(dic, k):
      """ Deletes a specified key from a given dictionary.
      >>> dictionary = {'foo': 1, 'bar': 2, 'baz': 3}
      >>> delete_key(dictionary, 'baz')
      >>> dictionary
      {'foo': 1, 'bar': 2}
      >>> delete_key(dictionary, 'nonexistent_key')
      >>> dictionary
      {'foo': 1, 'bar': 2}
      """
      if k in dic:
          del dic[k]
  
  
output:     if k in dic:
          del dic[k]