def get_forces(system):
    """
    get forces from a system as a dictionary

    arguments
        system : simtk.openmm.System
            system to query

    returns
        _dict : dict
            {force_name: (force, force_idx)} where force_name is a string, force is a simtk.openmm.Force, and
            force_idx is the index of the force
    """
    _dict = {}
    for force_idx, force in enumerate(system.getForces()):
        _dict[force.__class__.__name__] = (force, force_idx)
    return _dict