Tests whether end of file has been reached for the current input stream or for the input stream Stream.
at_end_of_file/[0,1] checks if end of file
has been reached for the specified input stream.
An input stream reaches end of file when all characters
except the file border code (-1 by default) of the stream have been read.
It remains at end of file after the file border code has been read.
Stream errors (see ref-iou-sfh-est), plus:
at_end_of_file/[0,1] peeks ahead for next input character if there is
no character available on the buffer of the specified input stream.
at_end_of_file/[0,1] to check for end of file condition
is more portable among different operating systems than checking end of file
by the character code (for example, peek_char(-1)).