see(X)

If X is an open input stream, then it is made the current input stream.

If X is an atom, it is taken to be a file name and
	- if there is an input stream currently associated with a file
	  of that name then it is made the current input stream.( If
	  more than one input stream is associated with X, one is
	  chosen arbitrarily)
	- otherwise ,that file is opened, a stream created and and set
	  to be the current input stream
