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: volt.m
    path of file: ./repos/chebfun/@chebfun2
    
    the code of the file until where you have to start completion: function f = volt(K, v)
%VOLT      Volterra integral operator for CHEBFUN2.
%   V = VOLT(K, f) returns a row CHEBFUN resulting from the integral
%
%      f(x) = (K*v)(x) = int( K(x,y) v(y), y=a..x ),

    
function f = volt(K, v)
%VOLT      Volterra integral operator for CHEBFUN2.
%   V = VOLT(K, f) returns a row CHEBFUN resulting from the integral
%
%      f(x) = (K*v)(x) = int( K(x,y) v(y), y=a..x ),
%
%   where K is defined on a domain [a,b]x[a,b].
%
%   The kernel function K(x,y) must be a smooth CHEBFUN2 defined on a square
%   domain.
%
% Example:
%   f = volt(chebfun2(@(x,y) exp(x-y)),chebfun('x'));
%
% See also FRED.

% Copyright 2017 by The University of Oxford and The Chebfun2 Developers.
% See http://www.chebfun.org/ for Chebfun2 information.

if ( ~isa(K, 'chebfun2') )
    error('CHEBFUN:CHEBFUN2:volt:input', ...
          'First argument must be a CHEBFUN2.');
end