code: def channel_first_axis_to_IR(index):
      if index == 0:
          return 0
      elif index == 1:
          return -1
      else:
          return index - 1
  
file_path: MMdnn/mmdnn/conversion/common/DataStructure/parser.py
imports: import numpy
  import mmdnn.conversion.common.IR.graph_pb2
  from mmdnn.conversion.common.IR.graph_pb2 import NodeDef, GraphDef, DataType
label_desc: Use image node_id 13 for calling the Parser obj's underlying member method code with example usage: obj.channel_first_axis_to_IR(index) and returns: int, unknown, unknown