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: PRset.m
    path of file: ./repos/IRtools/Extra
    
    the code of the file until where you have to start completion: function options = PRset(varargin)
%PRset Set options for IR Tools test problems
%
% options = PRset('param1',value1,'param2',value2,...)
%
% Create/alter options 
    
function [valid, errmsg] = PosInteger(field,value)
% Any positive real integer
valid =  isreal(value) && isscalar(value) && (value > 0) && value == floor(value) ;

if ~valid
  errmsg = sprintf('Invalid value for OPTIONS parameter %s: must be a positive real integer.',field);
else
  errmsg = '';
end