anchor.diff:          default = {};
           example = { l = "less"; gco = "git checkout"; };
           description = ''
  -          Set of abbreviations for fish shell.
  +          An attribute set that maps aliases (the top level attribute names
  +          in this option) to abbreviations. Abbreviations are expanded with
  +          the longer phrase after they are entered.
           '';
         };
   
  
positive.code:         type = types.lines;
          default = "";
          description = ''
            Shell script code called during fish shell initialisation.
          '';
        };
  
  
negative.code:         type = types.lines;
          default = "";
          description = ''
            Shell script code called during fish login shell
            initialisation.
          '';
        };
  
  