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: vertcat.m
    path of file: ./repos/OPTI/Utilities/@adiff
    
    the code of the file until where you have to start completion: function c = vertcat(varargin)
% VERTCAT does vertical concatenation [a;b;...] of adiff objects and/or
% column vectors.
% The horizontal concatenation [a,b,...] is NOT supported

    
function c = vertcat(varargin)
% VERTCAT does vertical concatenation [a;b;...] of adiff objects and/or
% column vectors.
% The horizontal concatenation [a,b,...] is NOT supported

% Find the final dimensions of the result
nr = 0; nc = 0; issp = logical(0); root=[];
for i=1:length(varargin)
   if isa(varargin{i},'adiff')
      nr = nr+length(varargin{i});
      nvar = size(varargin{i}.dx,2);
      issp = issp&issparse(varargin{i});
      if isempty(root)|isempty(root.root), root = varargin{i}; end