anchor.diff:  
   %%--------------------------------------------------------------------
   %% Function: fetch(Key, List)
  -%%           Key = string(), the name of a field in a sip message 
  -%%           header - all RFC 3261 formats are accepted 
  +%%           Key = string(), the name of a field in a sip message
  +%%           header - all RFC 3261 formats are accepted
   %%           List = keylist record()
   %% Descrip.: return the contens that of the header that matches Key
   %% Returns : E#keyelem.item
  
positive.code: 
  %% Function: filter(Func, Keylist)
  %%           Func = fun(E) -> bool(), predicate function
  %%           Keylist = list() of keyelem record() 
  %% Descrip.: 
  %% Returns : keylist record()
  filter(Func, Keylist) when record(Keylist, keylist) ->
      Pred = fun(Elem) ->
  
negative.code: 
  %%--------------------------------------------------------------------
  %% Function: to_lower_list(Keys)
  %%           Keys = list() of string(), the name of a field in a sip
  %%           message
  %% Descrip.: convert header key, to a standard format - lowercase and
  %%           verbose string()
  %% Returns : list() of string()
  %%--------------------------------------------------------------------
  to_lower_list(Keys) ->
  