input: Write a function to list the contents of a directory using Python's os module. The function should return a list of filenames and directories in the specified path. If no path is provided, it should default to the current working directory.
  assert list_directory_contents('')==['file1.txt', 'file2.txt', 'directory1', 'directory2']
  assert list_directory_contents('./subdir')==['file3.txt', 'file4.txt']
  assert list_directory_contents('./nonexistent')==[]
  assert list_directory_contents('..')==['parent_file1.txt', 'parent_file2.txt', 'subdirectory']
output: def list_directory_contents(path='.'):
      import os
      try:
          return os.listdir(path)
      except FileNotFoundError:
          return []