Add 2020 source files for real

2020/burton/check_be.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+prog="$1"
+: ${prog:=prog_be}
+
+check_code() {
+    /bin/echo -n "$1 "; $prog $1 | rev
+}
+
+seq 0 255 | while read a; do
+    check_code "$a"
+done | pr -t -w120 -8