Implement word, wordlist, words, firstword, and lastword
diff --git a/test/err_word_zero.mk b/test/err_word_zero.mk
new file mode 100644
index 0000000..9b6efee
--- /dev/null
+++ b/test/err_word_zero.mk
@@ -0,0 +1,2 @@
+test:
+	echo $(word 0, foo bar)