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: CatValMul.m
    path of file: ./repos/d4m/matlab_src
    
    the code of the file until where you have to start completion: function AB = CatValMul(A,B);
%CatValMul: Perform matrix multiply and concatenate colliding values.

    
function AB = CatValMul(A,B);
%CatValMul: Perform matrix multiply and concatenate colliding values.
%Associative array user function.
%  Usage:
%    AB = CatValMul(A,B)
%  Inputs:
%    A = associative array with string values
%    B = associative array with string values
% Outputs:
%    AB = associative array with string value keys representing concatenated values of collisions.

  if ((IsClass(A,'Assoc') && ischar(Val(A))) && (IsClass(B,'Assoc') && ischar(Val(B))))
    AB = Abs0(A)*Abs0(B);

    % Trim down to just what we need.
    A1 = A(Row(AB),:);     B1 = B(:,Col(AB));
    A2 = A1(:,Row(B1));    B2 = B1(Col(A1),:);
    A2size = size(A2);     B2size = size(B2);

    A2adj = Adj(A2);
    A2val = Val(A2);
    A2valMat = Str2mat(A2val);

    B2adj = Adj(B2);
    B2valMat = Str2mat(Val(B2));

    % Set concatenation separator.
    sep = A2val(end