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: pos2transform.m
    path of file: ./repos/fieldtrip/utilities/private
    
    the code of the file until where you have to start completion: function [transform] = pos2transform(pos, dim)

% POS2TRANSFORM reconstructs a transformation matrix from an ordered list 
% of positions.
%
% Use as
%   [transform] = pos2transform(pos, dim)
% where pos is an ordered list of positions that should specify a full 3D volume.
%
% The output transform is a 4x4 homogenous transformation matrix which transforms
% from 'voxelspace' into the positions provided in the input
%
% See also POS2DIM

% Copyright (C) 2009, Jan-Mathijs Schoffelen

    
function [transform] = pos2transform(pos, dim)

% POS2TRANSFORM reconstructs a transformation matrix from an ordered list 
% of positions.
%
% Use as
%   [transform] = pos2transform(pos, dim)
% where pos is an ordered list of positions that should specify a full 3D volume.
%
% The output transform is a 4x4 homogenous transformation matrix which transforms
% from 'voxelspace' into the positions provided in the input
%
% See also POS2DIM

% Copyright (C) 2009, Jan-Mathijs Schoffelen

if nargin>1
  % do nothing
else
  dim = pos2dim(pos);
end