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: gmux_CPD.m
    path of file: ./repos/bnt/BNT/CPDs/@gmux_CPD
    
    the code of the file until where you have to start completion: function CPD = gmux_CPD(bnet, self, varargin)
% GMUX_CPD Make a Gaussian multiplexer node
%
% CPD = gmux_CPD(bnet, node, ...) is used similarly to gaussian_CPD,
% except we assume there is exactly one discrete parent (call it M)
% which is used to select which cts parent to pass through to the output.
% i.e., we define P(Y=y|M=m, X1, ..., XK) = N(y | W(m)*x(m) + mu(m), Sigma(m))
% where Y represents this node, and the Xi's are the cts parents.
% All the Xi must have the same size, and the num values for M must be K.
%
% Currently the params for this kind of CPD cannot be learned.

    
function CPD = gmux_CPD(bnet, self, varargin)
% GMUX_CPD Make a Gaussian multiplexer node
%
% CPD = gmux_CPD(bnet, node, ...) is used similarly to gaussian_CPD,
% except we assume there is exactly one discrete parent (call it M)
% which is used to select which cts parent to pass through to the output.
% i.e., we define P(Y=y|M=m, X1, ..., XK) = N(y | W(m)*x(m) + mu(m), Sigma(m))
% where Y represents this node, and the Xi's are the cts parents.
% All the Xi must have the same size, and the num values for M must be K.
%
% Currently the params for this kind of CPD cannot be learned.
%
% Optional arguments [ default in brackets ]
%
% mean       - mu(:,i) is the mean given M=i [ zeros(Y,K) ]
% cov        - Sigma(:,:,i) is the covariance given M=i [ repmat(1*eye(Y,Y), [1 1 K]) ]
% weights    - W(:,:,i) is the regression matrix given M=i [ randn(Y,X,K) ]

if nargin==0
  % This occurs if we are trying to load an object from a file.
  CPD = init_fields;
  clamp = 0;
  CPD = class(CPD, 'gmux_CPD', generic_CPD(clamp));
  return;
elseif isa(bnet, 'gmux_CPD')
  % This might occur if we are copying an object.
  CPD = bnet;
  return;
end