diamond operator in Perl

<> to read the file

@ARGV array: This array is a special array preset by the Perl interpreter as the list of the invocation arguments. In other words, this is like any other array, but when your program starts, @ARGV is already stuffed full of the list of invocation arguments.

@ARGV = qw# a b c #; # force these files to be read

while (<>){

chomp;

print "it was $_ that i saw";

}