key in map syntax

vlib/builtin/map.v

@@ -170,6 +170,11 @@ fn (m map) get(key string, out voidptr) bool {
 }
 
 pub fn (m map) exists(key string) bool {
+	panic('map.exists(key) was removed from the language. Use `key in map` instead.') 
+	return false 
+}
+
+fn (m map) _exists(key string) bool {
 	return !isnil(m.root) && m.root.find2(key, m.element_size) 
 }
 

vlib/builtin/map_test.v

@@ -21,6 +21,7 @@ fn test_map() {
 	assert m['hi'] == 80
 	assert m['hello'] == 101 
 	assert m.size == 2 
+	assert 'hi' in m 
 	mut sum := 0
 	mut key_sum := '' 
 	// Test `for in`