code: def get_existing_symbol(name):
      global k_used_symbols
      if name not in k_used_symbols:
          msg = "Symbol name {} does not exist"
          raise ValueError(msg.format(name))
      return k_used_symbols[name]
  
imports: from collections import defaultdict
  from typing import Dict, List
  import numpy
  import sympy
  from coremltools import _logger
  from coremltools.converters.mil._deployment_compatibility import AvailableTarget
  from coremltools.converters.mil.input_types import InputType
  from coremltools.converters.mil.mil.input_type import InternalInputType
  from coremltools.converters.mil.mil.ops.helper import _get_version_of_op
  from coremltools.converters.mil.mil.var import ListVar
  from .None import types
  from .block import Function
  from .operation import Operation
  from .types.symbolic import k_num_internal_syms, k_used_symbols
  from .var import Var
label_desc: Use image node_id 3 for calling a global function with example usage: get_existing_symbol(name) and returns: k_used_symbols