def _extract_placeholders_from_exir_program(
    exported_program  # torch.export.ExportedProgram
) -> Dict[str, torch.fx.Node]:
    """
    Given:
        exported_program: torch.export.ExportedProgram
    Return:
        placeholders: dictionary mapping names to placeholder nodes
    """
    placeholders = {}
    for node in exported_program.graph_module.graph.nodes:
        if node.op == "placeholder":
            placeholders[node.name] = node
    return placeholders

    Given:
        exported_program: torch.export.ExportedProgram
    Return:
        placeholders: dictionary mapping names to placeholder nodes
    
coremltools/converters/mil/frontend/torch/exir_utils.py