Add Even Odd in Elvish (#4213)

Author: Kaamkiya

archive/e/elvish/even-odd.elv

@@ -0,0 +1,17 @@
+use re
+
+if (> 1 (count $args)) {
+  echo "Usage: please input a number"
+  exit 1
+}
+
+if (not (re:match '^[+-]?[0-9]+(\.[0-9]+)?$' $args[0])) {
+  echo "Usage: please input a number"
+  exit 1
+}
+
+if (== 0 (% $args[0] 2)) {
+  echo Even
+} else {
+  echo Odd
+}