def pull_force_by_name(system, force_name = 'NonbondedForce', **kwargs):
    """
    pull a force object from a system for querying

    arguments
        system : simtk.openmm.openmm.System
            system that will be queried
        force_name : str, default 'NonbondedForce'
            force name that will be matched

    returns
        force : simtk.openmm.openmm.Force
            matched force
    """
    forces = system.getForces()
    force_dict = {force.__class__.__name__: force for force in forces}
    try:
        force = force_dict[force_name]
    except Exception as e:
        raise Exception(f"{e}")
    return force