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: spm_input.m
    path of file: ./repos/bspm/thirdparty/spm12
    
    the code of the file until where you have to start completion: function varargout = spm_input(varargin)
% Comprehensive graphical and command line input function
% FORMATs (given in Programmers Help)
%_______________________________________________________________________
%
% spm_input handles most forms of interactive user input for SPM.

    
function varargout = spm_input(varargin)
% Comprehensive graphical and command line input function
% FORMATs (given in Programmers Help)
%_______________________________________________________________________
%
% spm_input handles most forms of interactive user input for SPM.
% (File selection is handled by spm_select.m)
%
% There are five types of input: String, Evaluated, Conditions, Buttons
% and Menus:  These prompt for string input; string input which is
% evaluated to give a numerical result; selection of one item from a
% set of buttons; selection of an item from a menu.
%
% - STRING, EVALUATED & CONDITION input -
% For STRING, EVALUATED and CONDITION input types, a prompt is
% displayed adjacent to an editable text entry widget (with a lilac
% background!). Clicking in the entry widget allows editing, pressing
% <RETURN> or <ENTER> enters the result. You must enter something,
% empty answers are not accepted. A default response may be pre-specified
% in the entry widget, which will then be outlined. Clicking the border
% accepts the default value.
%
% Basic editing of the entry widget is supported *without* clicking in
% the widget, provided no other graphics widget has the focus. (If a
% widget has the focus, it is shown highlighted with a thin coloured
% line. Clicking on the window background returns the focus to the
% window, enabling keyboard accelerators.). This enables you to type
% responses to a sequence of questions without having to repeatedly
% click the mouse in the text widgets. Supported are BackSpace and
% Delete, line kill (^U). Other standard ASCII characters are append