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: engraving.m
    path of file: ./repos/gptoolbox/mesh
    
    the code of the file until where you have to start completion: function [V,F] = engraving(im,w,t,s,l)
  % ENGRAVING Create an engraving of an image
  %
  % [V,F] = engraving(im,w,t,s)
  %
  % Inputs:
  %   im  width by height grayscale image
  %   w   desired width of engraving model (in mm)
  %   t  desired thickness of engraving model (in mm)
  %   s  desired span of thickness devoted to levels (in mm)
  %   l  number of levels
  % Outputs:
  %   V  #V by 3 list of vertex positions
  %   F  #F by 3 list of triangle indices
  %
  % Example:
  %  % load image
  %  im = imresize(rgb2gray(im2double(imread('hans-hass.jpg'))),0.5);
  %  % pad image by 10% of width
  %  im = padarray(im,ceil(0.1*repmat(size(im,2),1,2)));
  %  % engrave: 50mm wide, 5mm thick, 1mm devoted to 4 layers
  %  [V,F] = engraving(im,50,5,1,4);
  %

    
function [V,F] = engraving(im,w,t,s,l)
  % ENGRAVING Create an engraving of an image
  %
  % [V,F] = engraving(im,w,t,s)
  %
  % Inputs:
  %   im  width by height grayscale image
  %   w   desired width of engraving model (in mm)
  %   t  desired thickness of engraving model (in mm)
  %   s  desired span of thickness devoted to levels (in mm)
  %   l  number of levels
  % Outputs:
  %   V  #V by 3 list of vertex positions
  %   F  #F by 3 list of triangle indices
  %
  % Example:
  %  % load image
  %  im = imresize(rgb2gray(im2double(imread('hans-hass.jpg'))),0.5);
  %  % pad image by 10% of width
  %  im = padarray(im,ceil(0.1*repmat(size(im,2),1,2)));
  %  % engrave: 50mm wide, 5mm thick, 1mm devoted to 4 layers
  %  [V,F] = engraving(im,50,5,1,4);
  %

  assert(isfloat(im));
  [V,F] = create_regular_grid(size(im,2),size(im,1),0,0);
  V(:,1) = V(:,1)*w;
  V(:,2) = (1-V(:,2))*size(im,1)/size(im,2)*w;
  [V,F] = extrude(V,F);
  V(:,3) = V(:,3)*t;
  V(1:numel(im),3) = V(1:numel(im),3)-s*round(im(:)*(l-1))/(l-1);

end