code: def _import_tf():
      """Tries to import tensorflow."""
      global tf
      if tf is None:
          import tensorflow as tf
      return tf
  
imports: from ..core.base import CONVOLUTION_LAYER_VALUES
  from ..core.base import CONVOLUTION_OUTPUT_GRADIENTS
  from ..core.base import INPUT_OUTPUT_GRADIENTS
  from ..core.base import OUTPUT_LAYER_VALUES
label_desc: Use image node_id 1 for calling a global function with example usage: _import_tf() and returns: tf