+/* read_yes_or_no_if_tty.h -- get a yes/no answer from the user
+ *
+ * This code is Copyright (c) 2017, by the authors of nmh. See the
+ * COPYRIGHT file in the root directory of the nmh distribution for
+ * complete copyright information. */
+
+/*
+ * If standard input is not a tty, return 1 without printing anything. Else,
+ * print null-terminated PROMPT to and flush standard output. Read answers from
+ * standard input until one is "yes" or "no", returning 1 for "yes" and 0 for
+ * "no". Also return 0 on EOF.
+ */
+int read_yes_or_no_if_tty(const char *);