def METHOD_NAME(spec):
    """Get import code block for a craft spec.
    Parameters
    ----------
    spec : str, sktime/skbase compatible object specification
        i.e., a string that executes to construct an object if all imports were present
        imports inferred are of any classes in the scope of ``all_estimators``
        option 1: a string that evaluates to an estimator
        option 2: a sequence of assignments in valid python code,
            with the object to be defined preceded by a "return"
            assignments can use names of classes as if all imports were present
    Returns
    -------
    import_str : str
        python code consisting of all import statements required for spec
        imports cover object/estimator classes found as sub-strings of spec
    """
    register = dict(all_estimators())
    import_strs = []
    for x in _extract_class_names(spec):
        if x not in register.keys():
            raise RuntimeError(
                f"class {x} is required to build spec, but was not found "
                "in all_estimators scope"
            )
        cls = register[x]
        import_str = f"from {cls.__module__} import {x}"
        import_strs += [import_str]
    if len(import_strs) == 0:
        imports_str = ""
    else:
        imports_str = "\n".join(sorted(import_strs))
    return imports_str