fix: print in hex format for non-ascii unicode

hw1/src/argo.c

@@ -903,9 +903,19 @@ int argo_write_string(ARGO_STRING *s, FILE *f)
                 }
             }
             else
+            {
+                if (c <= 0xff)
                 {
                     fprintf(f, "%c", *c);
                 }
+                else if (c <= 0xfff)
+                {
+                    fprintf(f, "\\u0%x", c);
+                }
+                else {
+                    fprintf(f, "\\u%x", c);
+                }
+            }
             break;
         }
     }