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: per_vertex_normals.m
    path of file: ./repos/gptoolbox/mesh
    
    the code of the file until where you have to start completion: function N = per_vertex_normals(V,F,varargin)
  % PER_VERTEX_NORMALS  Compute per-vertex (area-weighted) normals over a mesh % (V,F)
  %
  % N = per_vertex_normals(V,F)
  %
  % Inputs:
  %   V  #V by 3 list of vertex positions
  %   F  #F by 3 list of triangle indices
  %   Optional:
  %     'Weighting' followed by one of the following:
  %        {'area'} weighting
  %        'uniform' weighting

    
function N = per_vertex_normals(V,F,varargin)
  % PER_VERTEX_NORMALS  Compute per-vertex (area-weighted) normals over a mesh % (V,F)
  %
  % N = per_vertex_normals(V,F)
  %
  % Inputs:
  %   V  #V by 3 list of vertex positions
  %   F  #F by 3 list of triangle indices
  %   Optional:
  %     'Weighting' followed by one of the following:
  %        {'area'} weighting
  %        'uniform' weighting
  %        'angle' weighting
  % Outputs:
  %   N  #V by 3 list of vertex normals
  %

  weighting = 'area';
  U = [];
  R = [];
  % default values
  % Map of parameter names to variable names
  params_to_variables = containers.Map( ...
    {'Weighting'},{'weighting'});
  v = 1;
  while v <= numel(varargin)
    param_name = varargin{v};
    if isKey(params_to_variables,param_name)
      assert(v+1<=numel(varargin));
      v = v+1;
      % Trick: use feval on anonymous function to use assignin to this workspace
      feval(@()assignin('caller',params_to_variables(param_name),varargin{v}));
    else
      error('Unsupported parameter: %s',varargin{v});
    end