my @node_numbers;

if (@ARGV) {
   @node_numbers = @ARGV;
} else {
   die(<<"EOF") if -t STDIN;
#####################################
#
#  use args or < a text file
# 
#####################################
EOF

   { local $/; @node_numbers = split(' ', <STDIN>); }
}

# Do rest of code after here using @node_numbers