anchor.diff:  
     /* Depending on the boolean `cond', return either the given string
        or the empty string. Useful to concatenate against a bigger string.
  +
  +     Type: optionalString :: bool -> string -> string
   
        Example:
          optionalString true "some-string"
  
positive.code: 
    /* Create a fixed width string with additional prefix to match
       required width.
  
       Example:
         fixedWidthString 5 "0" (toString 15)
  
negative.code: 
    /* Converts an ASCII string to upper-case.
  
       Type: toUpper :: string -> string
  
       Example:
         toUpper "home"
         => "HOME"
  