How to use the flopy.pakbase.Package function in flopy

def __init__(self, model, itrnsp=1, ibctcb=0, mcomp=1, ic_ibound_flg=1,
                 itvd=1, iadsorb=0, ict=0, cinact=-999., ciclose=1.e-6,
                 idisp=1, ixdisp=0, diffnc=0., izod=0, ifod=0, icbund=1,
                 porosity=0.1, bulkd=1., arad=0., dlh=0., dlv=0., dth=0.,
                 dtv=0., sconc=0.,
                 extension='bct', unitnumber=None):

        # set default unit number of one is not specified
        if unitnumber is None:
            unitnumber = ModflowBct.defaultunit()

        # Call ancestor's init to set self.parent, extension, name and unit
        # number
        Package.__init__(self, model, extension, ModflowBct.ftype(),
                         unitnumber)

        self.url = 'bct.htm'
        nrow, ncol, nlay, nper = self.parent.nrow_ncol_nlay_nper
        self.itrnsp = itrnsp
        self.ibctcb = ibctcb
        self.mcomp = mcomp
        self.ic_ibound_flg = ic_ibound_flg
        self.itvd = itvd
        self.iadsorb = iadsorb
        self.ict = ict
        self.cinact = cinact
        self.ciclose = ciclose
        self.idisp = idisp
        self.ixdisp = ixdisp
        self.diffnc = diffnc

the ModflowSwi2 class as `flopy.modflow.ModflowSwi2`.

Additional information for this MODFLOW package can be found at the `Online
MODFLOW Guide
`_.

"""
import sys

import numpy as np

from ..pakbase import Package
from ..utils import Util2d, Util3d


class ModflowSwi2(Package):
    """
    MODFLOW SWI2 Package Class.

    Parameters
    ----------
    model : model object
        The model object (of type :class:`flopy.modflow.mf.Modflow`) to which
        this package will be added.
    nsrf : int
        number of active surfaces (interfaces). This equals the number of zones
        minus one. (default is 1).
    istrat : int
        flag indicating the density distribution. (default is 1).
    iswizt : int
        unit number for zeta output. (default is None).
    ipakcb : int

import os
from ..mbase import BaseModel
from ..pakbase import Package
from ..modflow import Modflow
from ..mt3d import Mt3dms
from .swtvdf import SeawatVdf
from .swtvsc import SeawatVsc
from ..discretization.structuredgrid import StructuredGrid
from flopy.discretization.modeltime import ModelTime


class SeawatList(Package):
    """
    List Package class
    """

    def __init__(self, model, extension='list', listunit=7):
        Package.__init__(self, model, extension, 'LIST', listunit)
        return

    def __repr__(self):
        return 'List package class'

    def write_file(self):
        # Not implemented for list class
        return

model.add_output_file(ipakcb, fname=fname,
                                  package=ModflowRch.ftype())
        else:
            ipakcb = 0

        # Fill namefile items
        name = [ModflowRch.ftype()]
        units = [unitnumber]
        extra = ['']

        # set package name
        fname = [filenames[0]]

        # Call ancestor's init to set self.parent, extension, name and
        # unit number
        Package.__init__(self, model, extension=extension, name=name,
                         unit_number=units, extra=extra, filenames=fname)

        nrow, ncol, nlay, nper = self.parent.nrow_ncol_nlay_nper
        self.heading = '# {} package for '.format(self.name[0]) + \
                       ' {}, '.format(model.version_types[model.version]) + \
                       'generated by Flopy.'
        self.url = 'rch.htm'

        self.nrchop = nrchop
        self.ipakcb = ipakcb
        self.rech = Transient2d(model, (nrow, ncol), np.float32,
                                rech, name='rech_')
        if self.nrchop == 2:
            self.irch = Transient2d(model, (nrow, ncol), np.int32,
                                    irch + 1,
                                    name='irch_')

def __init__(self, model, mp_name_file='mp.nam', mp_list_file='mp.list',
                 option_flags=[1, 2, 1, 1, 1, 2, 2, 1, 2, 1, 1, 1],
                 ref_time=0, ref_time_per_stp=[0, 0, 1.0], stop_time=None,
                 group_name=['group_1'], group_placement=[[1, 1, 1, 0, 1, 1]],
                 release_times=[[1, 1]],
                 group_region=[[1, 1, 1, 1, 1, 1]], mask_nlay=[1],
                 mask_layer=[1], mask_1lay=[1], face_ct=[1],
                 ifaces=[[6, 1, 1]], part_ct=[[1, 1, 1]],
                 time_ct=1, release_time_incr=1, time_pts=[1],
                 particle_cell_cnt=[[2, 2, 2]],
                 cell_bd_ct=1, bud_loc=[[1, 1, 1, 1]], trace_id=1, stop_zone=1,
                 zone=1, retard_fac=1.0, retard_fcCB=1.0, strt_file=None,
                 extension='mpsim'):

        # Call ancestor's init to set self.parent, extension, name and unit number
        Package.__init__(self, model, extension, 'MPSIM', 32)
        nrow, ncol, nlay, nper = self.parent.mf.nrow_ncol_nlay_nper

        self.heading1 = '# MPSIM for Modpath, generated by Flopy.'
        self.heading2 = '#'
        self.mp_name_file = '{}.{}'.format(model.name, 'mpnam')
        self.mp_list_file = '{}.{}'.format(model.name, 'mplst')
        options_list = ['SimulationType', 'TrackingDirection',
                        'WeakSinkOption', 'WeakSourceOption',
                        'ReferenceTimeOption', 'StopOption',
                        'ParticleGenerationOption', 'TimePointOption',
                        'BudgetOutputOption', 'ZoneArrayOption',
                        'RetardationOption',
                        'AdvectiveObservationsOption']
        self.option_flags = option_flags
        options_dict = dict(list(zip(options_list, option_flags)))
        self.options_dict = options_dict

if filenames is None:
            filenames = [None]
        elif isinstance(filenames, str):
            filenames = [filenames]

        # Fill namefile items
        name = [ModflowSwr1.ftype()]
        units = [unitnumber]
        extra = ['']

        # set package name
        fname = [filenames[0]]

        # Call ancestor's init to set self.parent, extension, name and
        # unit number
        Package.__init__(self, model, extension=extension, name=name,
                         unit_number=units, extra=extra, filenames=fname)

        # check if a valid model version has been specified
        if model.version == 'mf2k' or model.version == 'mfusg':
            err = 'Error: cannot use {} package with model version {}'.format(
                self.name, model.version)
            raise Exception(err)

        self.heading = '# {} package for '.format(self.name[0]) + \
                       ' {}, '.format(model.version_types[model.version]) + \
                       'generated by Flopy.'
        self.url = 'swr1.htm'

        self.parent.add_package(self)

the ModflowFhb class as `flopy.modflow.ModflowFhb`.

Additional information for this MODFLOW package can be found at the `Online
MODFLOW Guide
`_.

"""
import sys

import numpy as np

from ..pakbase import Package
from ..utils.recarray_utils import create_empty_recarray


class ModflowFhb(Package):
    """
    MODFLOW Flow and Head Boundary Package Class.

    Parameters
    ----------
    model : model object
        The model object (of type :class:`flopy.modflow.mf.ModflowFhb`) to
        which this package will be added.
    nbdtim : int
        The number of times at which flow and head will be specified for all
        selected cells. (default is 1)
    nflw : int
        Number of cells at which flows will be specified. (default is 0)
    nhed: int
        Number of cells at which heads will be specified. (default is 0)
    ifhbss : int

def get_empty(ncells=0, aux_names=None, structured=True):
        # get an empty recarray that corresponds to dtype
        dtype = ModflowGhb.get_default_dtype(structured=structured)
        if aux_names is not None:
            dtype = Package.add_to_dtype(dtype, aux_names, np.float32)
        return create_empty_recarray(ncells, dtype, default_value=-1.0E+10)

vo.dtype, v,
                                                   name=vo.name_base,
                                                   fmtin=vo.fmtin,
                                                   locat=vo.locat))
                        value = new_list
                    elif isinstance(old_value[0], Util2d):
                        new_list = []
                        for vo, v in zip(old_value, value):
                            new_list.append(Util2d(self.parent, vo.shape,
                                                   vo.dtype, v,
                                                   name=vo.name,
                                                   fmtin=vo.fmtin,
                                                   locat=vo.locat))
                        value = new_list

        super(Package, self).__setattr__(key, value)