input: Write a function to list the contents of a directory using Python. The function should return a list of the contents of the specified directory. If the directory is empty, the function should return an empty list.
  assert list_directory_contents('/home/user/documents')==['file1.txt', 'file2.txt', 'folder1']
  assert list_directory_contents('/home/user/empty_folder')==[]
  assert list_directory_contents('/non/existent/path')==[]
output: import os
  
  def list_directory_contents(directory):
      if not os.path.exists(directory):
          return []
      return os.listdir(directory)