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: vl_argparse.m
    path of file: ./repos/Pedestrian_Alignment/matlab
    
    the code of the file until where you have to start completion: function [opts, args] = vl_argparse(opts, args, varargin)
%VL_ARGPARSE Parse list of parameter-value pairs.
%   OPTS = VL_ARGPARSE(OPTS, ARGS) updates the structure OPTS based on
%   the specified parameter-value pairs ARGS={PAR1, VAL1, ... PARN,
%   VALN}. If a parameter PAR cannot be matched to any of the fields
%   in OPTS, the function generates an error.
%
%   Parameters that have a struct value in OPTS are processed
%   recursively, updating the individual subfields.  This behaviour
%   can be suppressed by using VL_ARGPARSE(OPTS, ARGS, 'nonrecursive'),
%   in which case the struct value is copied directly (hence deleting any
%   existing subfield existing in OPTS). A direct copy occurrs also if the
%   struct value in OPTS is a structure with no fields. The nonrecursive
%   mode is especially useful when a processing time is a concern.
%
%   One or more of the (PAR, VAL) pairs in the argument list can be
%   replaced by a structure; in this case, the fields of the structure
%   are used as paramater names and the field values as parameter
%   values. This behaviour, while orthogonal to structure-valued parameters,
%   is also disabled in the 'nonrecursive' mode.
%
%   [OPTS, ARGS] = VL_ARGPARSE(OPTS, ARGS) copies any parameter in
%   ARGS that does not match OPTS back to ARGS instead of producing an
%   error. Options specified as structures are passed back as a list
%   of (PAR, VAL) pairs.
%
%   Example::
%     The function can be used to parse a list of arguments
%     passed to a MATLAB functions:
%
%        function myFunction(x,y,z,varargin)
%        opts.parameterName = defaultValue ;
%        opts = vl_argparse(opts, varargin)
%
%     If only a subset of the options should be parsed, for example
%     because the other options are interpreted by a subroutine, then
%     use the form
%
%        [opts, varargin] = vl_argparse(opts, varargin)
%
%     that copies back to VARARGIN any unknown parameter.
%

    
function [opts, args] = vl_argparse(opts, args, varargin)
%VL_ARGPARSE Parse list of parameter-value pairs.
%   OPTS = VL_ARGPARSE(OPTS, ARGS) updates the structure OPTS based on
%   the specified parameter-value pairs ARGS={PAR1, VAL1, ... PARN,
%   VALN}. If a parameter PAR cannot be matched to any of the fields
%   in OPTS, the function generates an error.
%
%   Parameters that have a struct value in OPTS are processed
%   recursively, updating the individual subfields.  This behaviour
%   can be suppressed by using VL_ARGPARSE(OPTS, ARGS, 'nonrecursive'),
%   in which case the struct value is copied directly (hence deleting any
%   existing subfield existing in OPTS). A direct copy occurrs also if the
%   struct value in OPTS is a structure with no fields. The nonrecursive
%   mode is especially useful when a processing time is a concern.
%
%   One or more of the (PAR, VAL) pairs in the argument list can be
%   replaced by a structure; in this case, the fields of the structure
%   are used as paramater names and the field values as parameter
%   values. This behaviour, while orthogonal to structure-valued parameters,
%   is also disabled in the 'nonrecursive' mode.
%
%   [OPTS, ARGS] = VL_ARGPARSE(OPTS, ARGS) copies any parameter in
%   ARGS that does not match OPTS back to ARGS instead of producing an
%   error. Options specified as structures are passed back as a list
%   of (PAR, VAL) pairs.
%
%   Example::
%     The function can be used to parse a list of arguments
%     passed to a MATLAB functions:
%
%        function myFunction(x,y,z,varargin)
%        opts.parameterName = defaultValue ;
%        opts = vl_argparse(opts, varargin)
%
%     If only a subset of the options should be parsed, for example
%     because the other options are interpreted by a subroutine, then
%     use the form
%
%        [opts, varargin] = vl_argparse(opts, varargin)
%
%     that copies back to VARARGIN any unknown parameter.
%
%   See also: VL_HELP().

% Copyright (C) 2015-16 Andrea Vedaldi and Karel Lenc.
% Copyright (C) 2007-12 Andrea Vedaldi and Brian Fulkerson.
% All rights reserved.
%
% Tishis file is part of the VLFeat library and is made available under
% the terms of the BSD license (see the COPYING file).

if ~isstruct(opts) && ~isobject(opts), error('OPTS must be a structure') ; end