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: propMapGridPlot.m
    path of file: ./repos/LADAC/propulsion/propeller_map-based
    
    the code of the file until where you have to start completion: function [] = propMapGridPlot( prop_grid, varargin )
%propMapGridPlot plots the map of a propeller.
% 
% Syntax:
%   propMapGridPlot( prop_grid )
%   propMapGridPlot( prop_grid, output_name )
% 
% Inputs:
%   prop_grid           propeller map grid (struct) as defined by the
%                       function propMapGridCreate
%   output_name         (optional) specify the z axis:
%                           'thrust'
%                           'torque'
%                           'power'
%                           empty:   thrust (default)
% 
% See also:
%   PROPMAPGRIDCREATE, PROPMAPFITPLOT

% Disclamer:
%   SPDX-License-Identifier: GPL-3.0-only
% 
%   Copyright (C) 2020-2022 Yannic Beyer
%   Copyright (C) 2022 TU Braunschweig, Institute of Flight Guidance
% *************************************************************************

    
function [] = propMapGridPlot( prop_grid, varargin )
%propMapGridPlot plots the map of a propeller.
% 
% Syntax:
%   propMapGridPlot( prop_grid )
%   propMapGridPlot( prop_grid, output_name )
% 
% Inputs:
%   prop_grid           propeller map grid (struct) as defined by the
%                       function propMapGridCreate
%   output_name         (optional) specify the z axis:
%                           'thrust'
%                           'torque'
%                           'power'
%                           empty:   thrust (default)
% 
% See also:
%   PROPMAPGRIDCREATE, PROPMAPFITPLOT

% Disclamer:
%   SPDX-License-Identifier: GPL-3.0-only
% 
%   Copyright (C) 2020-2022 Yannic Beyer
%   Copyright (C) 2022 TU Braunschweig, Institute of Flight Guidance
% *************************************************************************

[RPM_grid,V_grid] = meshgrid( prop_grid.RPM, prop_grid.V );

if isempty(varargin)
    Z = prop_grid.T;
    label = 'thrust, N';
else
    if strcmp(varargin{1},'thrust')
        Z = prop_grid.T;
        label = 'thrust, N';
    elseif strcmp(varargin{1},'torque')
        Z = prop_grid.Tau;
        label = 'torque, Nm';
    elseif strcmp(varargin{1},'power')
        Z = prop_grid.P;
        label = 'power, W';
    else
        error('The z axis was not specified correctly.')
    end