declaration/definition
declare #main-input has (binary-mode | text-mode | buffered | unbuffered)
    
 By default, #main-input is read from in text mode: this is the default setting for non-UNIX systems.
        Additionally, by default #main-input is buffered. declare #main-input has allows this
        behaviour to be changed explicitly. Changing both the mode and the buffering is possible, but requires two
        declarations.
      
 For example:
        
declare #main-input has binary-mode declare #main-input has unbuffered
 This declaration should always be used in preference to the newline declaration for performing
        binary input or output.