You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ft_headmodel_slab.m
    path of file: ./repos/fecgsyn/subfunctions/data-generation/libs/fieldtrip/forward
    
    the code of the file until where you have to start completion: function headmodel = ft_headmodel_slab(mesh1, mesh2, Pc, varargin)

% FT_HEADMODEL_SLAB creates an EEG volume conduction model that
% is described with an infinite conductive slab. You can think
% of this as two parallel planes containing a mass of conductive
% material (e.g. water) and externally to them a non-conductive material
% (e.g. air).
%
% Use as
%   headmodel = ft_headmodel_slab(mesh1, mesh2, Pc, varargin)
% where
%   mesh1.pos = Nx3 vector specifying N points through which the 'upper' plane is fitted 
%   mesh2.pos = Nx3 vector specifying N points through which the 'lower' plane is fitted 
%   Pc        = 1x3 vector specifying the spatial position of a point lying in the conductive slab 
%              (this determines the plane's normal's direction)
% 
% Optional arguments should be specified in key-value pairs and can include
%   'sourcemodel'  = 'monopole' 
%   'conductivity' = number ,  conductivity value of the conductive halfspace (default = 1)
% 
% See also FT_PREPARE_VOL_SENS, FT_COMPUTE_LEADFIELD

% Copyright (C) 2012, Donders Centre for Cognitive Neuroimaging, Nijmegen, NL
%

    
function headmodel = ft_headmodel_slab(mesh1, mesh2, Pc, varargin)

% FT_HEADMODEL_SLAB creates an EEG volume conduction model that
% is described with an infinite conductive slab. You can think
% of this as two parallel planes containing a mass of conductive
% material (e.g. water) and externally to them a non-conductive material
% (e.g. air).
%
% Use as
%   headmodel = ft_headmodel_slab(mesh1, mesh2, Pc, varargin)
% where
%   mesh1.pos = Nx3 vector specifying N points through which the 'upper' plane is fitted 
%   mesh2.pos = Nx3 vector specifying N points through which the 'lower' plane is fitted 
%   Pc        = 1x3 vector specifying the spatial position of a point lying in the conductive slab 
%              (this determines the plane's normal's direction)
% 
% Optional arguments should be specified in key-value pairs and can include
%   'sourcemodel'  = 'monopole' 
%   'conductivity' = number ,  conductivity value of the conductive halfspace (default = 1)
% 
% See also FT_PREPARE_VOL_SENS, FT_COMPUTE_LEADFIELD

% Copyright (C) 2012, Donders Centre for Cognitive Neuroimaging, Nijmegen, NL
%
% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org
% for the documentation and details.
%
%    FieldTrip is free software: you can redistribute it and/or modify
%    it under the terms of the GNU General Public License as published by
%    the Free Software Foundation, either version 3 of the License, or
%    (at your option) any later version.
%
%    FieldTrip is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.
%
%    You should have received a copy of the GNU General Public License
%    along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.
%
% $Id$

model = ft_getopt(varargin, 'sourcemodel', 'monopole');
cond  = ft_getopt(varargin, 'conductivity'); 

if isempty(cond)
  ft_warning('Conductivity was not specified, using 1');
  cond = 1;
end