code: def _is_valid_canonical_etype(canonical_etype):
      if not isinstance(canonical_etype, tuple):
          return False
  
      if len(canonical_etype) != 3:
          return False
  
      for t in canonical_etype:
          if not isinstance(t, str):
              return False
      return True
  
imports: import numpy
  from cugraph.gnn.dgl_extensions.utils.sampling import eid_n, src_n, dst_n
  from cugraph.utilities.utils import import_optional, MissingModule
label_desc: Use image node_id 2 for calling a global function with example usage: _is_valid_canonical_etype(canonical_etype) and returns: True, False, False, False