Write a valid crmod configuration file to filename.

    TODO: Modify configuration according to, e.g., 2D

def _write_crmod_file(filename):
    """Write a valid crmod configuration file to filename.

    TODO: Modify configuration according to, e.g., 2D
    """
    crmod_lines = [
        '***FILES***',
        '../grid/elem.dat',
        '../grid/elec.dat',
        '../rho/rho.dat',
        '../config/config.dat',
        'F                ! potentials ?',
        '../mod/pot/pot.dat',
        'T                ! measurements ?',
        '../mod/volt.dat',
        'F               ! sensitivities ?',
        '../mod/sens/sens.dat',
        'F                ! another dataset ?',
        '1                ! 2D (=0) or 2.5D (=1)',
        'F                ! fictitious sink ?',
        '1660             ! fictitious sink node number',
        'F                ! boundary values ?',
        'boundary.dat',
    ]

    with open(filename, 'w') as fid:
        [fid.write(line + '\n') for line in crmod_lines]