code: def _append_first(first, rest, axis):
      if first is None:
          return rest
      return tf.concat((first, rest), axis=axis)
  
imports: import tensorflow.compat.v2
  from tf_quant_finance import utils
label_desc: Use image node_id 12 for calling a global function with example usage: _append_first(first, rest, axis) and returns: tf, rest