<sep_list> - typically '<comma><space>'
<sep_list_pair> - typically '<space>and<space>'
<sep_list_end> - typically '<comma><space>and<space>' or '<comma><space>&<space>'  
defaults to cfg.presentation['sep_list'], cfg.presentation['sep_list_pair'], and cfg.presentation['sep_list_end']
if <sep_list_end> is specified, <sep_list> and <sep_list_pair> must also be supplied  
local function make_sep_list (count, list_seq, sep_list, sep_list_pair, sep_list_end)
local list = '';  
if not sep_list then -- set the defaults
sep_list = cfg.presentation['sep_list'];
sep_list_pair = cfg.presentation['sep_list_pair'];
sep_list_end = cfg.presentation['sep_list_end'];
end  
if 2 >= count then
list = table.concat (list_seq, sep_list_pair); -- insert separator between two items; returns list_seq[1] then only one item
elseif 2 < count then
list = table.concat (list_seq, sep_list, 1, count - 1); -- concatenate all but last item with plain list separator
list = table.concat ({list, list_seq[count]}, sep_list_end); -- concatenate last item onto end of <list> with final separator
end  
return list;
end  
--author-last1= and |author1-last= are represented as 'author-last#' and 'author#-last'.  
Because enumerated parameter |<param>1= is an alias of |<param>= we must test for both possibilities.  
Generates an error if more than one match is present.  
local function select_one (args, aliases_list, error_condition, index)
local value = nil; -- the value assigned to the selected parameter
local selected = ''; -- the name of the parameter we have chosen
local error_list = {};  
if index ~= nil then index = tostring(index); end  
for _, alias in ipairs (aliases_list) do -- for each alias in the aliases list
if alias:match ('#') then -- if this alias can be enumerated
if '1' == index then -- when index is 1 test for enumerated and non-enumerated aliases
value, selected = is_alias_used (args, alias, index, false, value, selected, error_list); -- first test for non-enumerated alias
end
value, selected = is_alias_used (args, alias, index, true, value, selected, error_list); -- test for enumerated alias
else
value, selected = is_alias_used (args, alias, index, false, value, selected, error_list); -- test for non-enumerated alias
end
end  
if #error_list > 0 and '' ~= error_condition then -- for cases where this code is used outside of extract_names
for i, v in ipairs (error_list) do
error_list[i] = wrap_style ('parameter', v);
end
table.insert (error_list, wrap_style ('parameter', selected));
set_message (error_condition, {make_sep_list (#error_list, error_list)});
end  
return value, selected;
end  
--[=[-------------------------< R E M O V E _ W I K I _ L I N K >----------------------------------------------  
Gets the display text from a wikilink like B or B gives B  
The str:gsub returns either A|B froma B or B from B or B from B (no wikilink markup).  
In l, l:gsub removes the link and pipe (if they exist); the second :gsub trims whitespace from the label
if str was wrapped in wikilink markup. Presumably, this is because without wikimarkup in str, there is no match
in the initial gsub, the replacement function l doesn't get called.  
]=]  
local function remove_wiki_link (str)
return (str:gsub ("%[%[([^%[%]]*)%]%]", function(l)
return l:gsub ("^[^|]*|(.*)$", "%1" ):gsub ("^%s*(.-)%s*$", "%1");
end));
end  
--[=[-------------------------< I S _ W I K I L I N K >--------------------------------------------------------  
Determines if str is a wikilink, extracts, and returns the wikilink type, link text, and display text parts.
If str is a complex wikilink (D):
returns wl_type 2 and D and L from D;
if str is a simple wikilink (D)
returns wl_type 1 and D from D and L as empty string;
if not a wikilink:
returns wl_type 0, str as D, and L as empty string.  
trims leading and trailing whitespace and pipes from L and D ([[L|]] and [[|D]] are accepted by MediaWiki and
treated like D; while [[|D|]] is not accepted by MediaWiki, here, we accept it and return D without the pipes).  
]=]  
local function is_wikilink (str)
local D, L
local wl_type = 2; -- assume that str is a complex wikilink D  
if not str:match ('^%[%^%+%]%]$') then -- is str some sort of a wikilink (must have some sort of content)
return 0, str, ''; -- not a wikilink; return wl_type as 0, str as D, and empty string as L
end  
L, D = str:match ('^%[%[([^|]+)|([^%]]+)%]%]$'); -- get L and D from D  
if not is_set (D) then -- if no separate display
D = str:match ('^%[%[([^%]]*)|*%]%]$'); -- get D from D or [[D|]]
wl_type = 1;
end  
D = mw.text.trim (D, '%s|'); -- trim white space and pipe characters
return wl_type, D, L or '';
end  
----------------------------< S T R I P _ A P O S T R O P H E _ M A R K U P >--------------------------------  
Strip wiki italic and bold markup from argument so that it doesn't contaminate COinS metadata.
This function strips common patterns of apostrophe markup. We presume that editors who have taken the time to
markup a title have, as a result, provided valid markup. When they don't, some single apostrophes are behind.  
Returns the argument without wiki markup and a number; the number is more-or-less meaningless except as a flag
to indicate that markup was replaced; do not rely on it as an indicator of how many of any kind of markup was
removed; returns the argument and nil when no markup removed  
local function strip_apostrophe_markup (argument)
if not is_set (argument) then
return argument, nil; -- no argument, nothing to do
end  
if nil == argument:find ( "''", 1, true ) then -- Is there at least one double apostrophe? If not, exit.
return argument, nil;
end  
local flag;
while true do
if argument:find ("**'", 1, true) then -- bold italic (5)
argument, flag = argument:gsub ("%'%'%'%'%'", ""); -- remove all instances of it
elseif argument:find ("**", 1, true) then -- italic start and end without content (4)
argument, flag=argument:gsub ("%'%'%'%'", "");
elseif argument:find ("'''", 1, true) then -- bold (3)
argument, flag=argument:gsub ("%'%'%'", "");
elseif argument:find ("''", 1, true) then -- italic (2)
argument, flag = argument:gsub ("%'%'", "");
else
break;
end
end  
return argument, flag; -- done
end  
----------------------------< S E T _ S E L E C T E D _ M O D U L E S >--------------------------------------  
Sets local cfg table to same (live or sandbox) as that used by the other modules.  
local function set_selected_modules (cfg_table_ptr)
cfg = cfg_table_ptr;  
end  
----------------------------< E X P O R T S >----------------------------------------------------------------  
return {
add_maint_cat = add_maint_cat, -- exported functions
add_prop_cat = add_prop_cat,
error_comment = error_comment,
has_accept_as_written = has_accept_as_written,
hyphen_to_dash = hyphen_to_dash,
in_array = in_array,
is_set = is_set,
is_wikilink = is_wikilink,
make_sep_list = make_sep_list,
make_wikilink = make_wikilink,
remove_wiki_link = remove_wiki_link,
safe_for_italics = safe_for_italics,
select_one = select_one,
set_message = set_message,
set_selected_modules = set_selected_modules,
strip_apostrophe_markup = strip_apostrophe_markup,
substitute = substitute,
wrap_style = wrap_style,  
z = z, -- exported table
}