code: def clear_cache():
      with DB.readwrite_cursor() as c:
          c.execute("DELETE FROM file")
          c.execute("DELETE FROM directory")
          c.execute("DELETE FROM storage_instance")
          c.execute("DELETE FROM series")
          c.execute("DELETE FROM study")
  
imports: import contextlib
  import getpass
  import logging
  import os
  import sqlite3
  import tempfile
  import warnings
  from io import BytesIO
  from os.path import join
  import numpy
  from nibabel.optpkg import optional_package
  from .nifti1 import Nifti1Header
label_desc: Use image node_id 6 for calling a global function with example usage: clear_cache() without return types