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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 _get_openscm_var_from_filepath(filepath):
 """ Determine the OpenSCM variable from a filepath. Uses MAGICC's internal, implicit, filenaming conventions. Parameters filepath : str Filepath from which to determine the OpenSCM variable. Returns ------- str The OpenSCM variable implied by the filepath. """

    reader = determine_tool(filepath, "reader")(filepath)
    openscm_var = convert_magicc7_to_openscm_variables(
        convert_magicc6_to_magicc7_variables(reader._get_variable_from_filepath())
    )

    return openscm_var