code: def assert_valid_label(label):
      """Assertion that passes if the supplied string is a valid label by all the
      rules of Cloud.
  
      """
      assert len(label) <= 63
  
      if label != "":
          # check that the output has only lowercase, letters, dashes or
          # underscores.
          assert re.match("^[a-z0-9_-]+$", label)
  
file_path: caliban/tests/caliban/platform/cloud/test_util.py
imports: import re
  import hypothesis.strategies
  from hypothesis import given
  import caliban.platform.cloud.util
label_desc: Use image node_id 3 for calling a global function with example usage: assert_valid_label(label) without return types