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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def set_transform_interface_params(spec, input_features, output_features, are_optional = False):
 """ Common utilities to set transform interface params. """

    input_features = _fm.process_or_validate_features(input_features)
    output_features = _fm.process_or_validate_features(output_features)

    # Add input and output features
    for (fname, ftype) in input_features:
        input_ = spec.description.input.add()
        input_.name = fname
        datatypes._set_datatype(input_.type, ftype)
        if are_optional:
            input_.type.isOptional = are_optional

    for (fname, ftype) in output_features:
        output_ = spec.description.output.add()
        output_.name = fname
        datatypes._set_datatype(output_.type, ftype)

    return spec