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: constructor.m
    path of file: ./repos/chebfun/@chebfun
    
    the code of the file until where you have to start completion: function [funs, ends] = constructor(op, dom, data, pref)
%CONSTRUCTOR   CHEBFUN constructor.
%   FUNS = CONSTRUCTOR(OP, DOM) constructs the piecewise components (known as
%   "FUNS") used by a CHEBFUN object to represent the function OP on the
%   interval DOM. OP must be a function_handle, string, numerical vector, or a
%   cell array containing a combination of these first three data types. In the
%   later case, the number of elements in the array must be one less than the
%   length of the DOM vector.
%
%   It is not expected that CHEBFUN.CONSTRUCTOR() be called directly, 
%
%   If OP is a function_handle or a string, it should be vectorised in that it
%   accepts a column vector of length N and return a matrix of size N x M. If M
%   ~= 1, we say the resulting CHEBFUN is "array-valued".
%
%   CONSTRUCTOR(OP, DOM, DATA, PREF), where DATA is a MATLAB structure and PREF
%   is a CHEBFUNPREF object, allows construction data and alternative
%   construction preferences to be passed to the constructor.  See CHEBFUNPREF
%   for more details on preferences.

    
function [funs, ends] = constructor(op, dom, data, pref)
%CONSTRUCTOR   CHEBFUN constructor.
%   FUNS = CONSTRUCTOR(OP, DOM) constructs the piecewise components (known as
%   "FUNS") used by a CHEBFUN object to represent the function OP on the
%   interval DOM. OP must be a function_handle, string, numerical vector, or a
%   cell array containing a combination of these first three data types. In the
%   later case, the number of elements in the array must be one less than the
%   length of the DOM vector.
%
%   It is not expected that CHEBFUN.CONSTRUCTOR() be called directly, 
%
%   If OP is a function_handle or a string, it should be vectorised in that it
%   accepts a column vector of length N and return a matrix of size N x M. If M
%   ~= 1, we say the resulting CHEBFUN is "array-valued".
%
%   CONSTRUCTOR(OP, DOM, DATA, PREF), where DATA is a MATLAB structure and PREF
%   is a CHEBFUNPREF object, allows construction data and alternative
%   construction preferences to be passed to the constructor.  See CHEBFUNPREF
%   for more details on preferences.
%
%   In particular, if PREF.SPLITTING = TRUE and OP is a function_handle or a
%   string, then the constructor adaptively introduces additional breakpoints
%   into the domain so as to better represent the function. These are returned
%   as the second output argument in [FUNS, END] = CONSTRUCTOR(OP, DOM).
%
%   The DATA structure input contains information which needs to be passed to
%   the lower layers about parameters which may affect the construction process.
%   Presently, the only fields CONSTRUCTOR expects DATA to have on input are
%   DATA.EXPONENTS and DATA.SINGTYPE, which convey information about end