code: def functionalize_loops(tfssa):
      """
      Functionalize all loops in an tfssa
      """
      done = False
      while not done:
          done = True
          for f in list(tfssa.functions.keys()):
              functionalize = FunctionalizeLoops()
              ret = functionalize.functionalize_loops(tfssa, f)
              if ret:
                  done = False
  
file_path: coremltools/coremltools/converters/mil/frontend/tensorflow/tf_graph_pass/functionalize_loops.py
imports: from coremltools import _logger
  from ..basic_graph_ops import connect_dests, connect_edge, connect_sources, delete_node, disconnect_edge, replace_dest, replace_source
  from ..parsed_tf_node import ParsedTFNode
  from ..tfssa import SSAFunction
  from .visitors import FindAllReachableNodes, FindImmediateDownstreamNodes, FindImmediateUpstreamNodes, FindSubgraph
label_desc: Use image node_id 1 for calling a global function with example usage: functionalize_loops(tfssa) without return types