How to use the pymars.drg.run_drg function in pymars

use the specified number of threads.

    """

    if method in ['DRG', 'DRGEP', 'PFA']:
        assert target_species, (
            'Need to specify at least one target species for graph-based reduction methods'
            )
    
    if not method and not run_sensitivity_analysis:
        raise ValueError(
            'Either a graph-based method or sensitivity analysis (or both) must be specified.'
            )
    
    if method == 'DRG':
        reduced_model = run_drg(
            model_file, ignition_conditions, psr_conditions, flame_conditions,
            error_limit, target_species, safe_species, phase_name=phase_name,
            threshold_upper=upper_threshold, num_threads=num_threads, path=path
            )    
    elif method == 'DRGEP':
        reduced_model = run_drgep(
            model_file, ignition_conditions, psr_conditions, flame_conditions, 
            error_limit, target_species, safe_species, phase_name=phase_name,
            threshold_upper=upper_threshold, num_threads=num_threads, path=path
            )
    elif method == 'PFA':
        reduced_model = run_pfa(
            model_file, ignition_conditions, psr_conditions, flame_conditions,
            error_limit, target_species, safe_species, phase_name=phase_name,
            num_threads=num_threads, path=path
            )