+# Install or copy LetsEncrypt certificates on/from server.
+#
+# First argument: server
+# Second argument: either "set" or "get" or "put"
+#
+# "set" install certbot on remote server and requests a new certificate
+# for it. This needs two more arguments: an e-mail address for future
+# communication with LetsEncrypt, and the domain for which to request
+# the certificate (might plausibly be equivalent to the first argument
+# though). This needs port 80 open on the server.
+#
+# "get" copies the server's /etc/letsencrypt to a local letsencrypt.tar.
+#
+# "set" copies a local letsencrypt.tar to the server's /etc/letsencrypt.