diff --git a/README.md b/README.md
index ccd0d41..969a037 100644
--- a/README.md
+++ b/README.md
@@ -117,7 +117,7 @@ This can be useful when you want to look at the unprocessed html without variabl
 
 ### conditionals
 To turn on or off entire blocks, `if`, `elif` can `else` be used.
-These commands must not be in multi-line comments.
+These commands can not be nested and must not appear in multi-line comments.
 Logical and `&&` and logical or `||` can be used to chain conditions.
 If a condition is true, the corresponding block is included while all other blocks are deleted.
 
@@ -133,6 +133,7 @@ If a condition is true, the corresponding block is included while all other bloc
 ```
 
 **Argument** Condition for `if` and `elif`, ignored for `else` and `endif`
+
 **Return Value** Empty String
 
 ---
diff --git a/html-preprocessor b/html-preprocessor
index 16008c4..4ab0e0b 100755
--- a/html-preprocessor
+++ b/html-preprocessor
@@ -69,11 +69,11 @@ exit_on_error_level = error_levels["serious"]
 """
 ************************************************************ UTILITY ************************************************************
 """
-DEBUG = True
+DEBUG = False
 def pdebug(*args, **keys):
     if DEBUG: print(*args, **keys)
 
-TRACE = True
+TRACE = False
 def ptrace(*args, **keys):
     if TRACE: print(*args, **keys)
 
@@ -283,6 +283,13 @@ def cmd_comment(args: str, variables:dict[str, str]={}) -> str:
 def cmd_uncomment(args: str, variables:dict[str, str]={}) -> str:
     return args
 
+def cmd_error(args: str, variables:dict[str, str]={}) -> str:
+    error(f"Encounted 'error' command: {args}", level=error_levels["critical"])
+    return ""
+def cmd_warning(args: str, variables:dict[str, str]={}) -> str:
+    error(f"Encounted 'warning' command: {args}", level=error_levels["light"])
+    return ""
+
 
 command2function:dict[str, Callable[[str, dict[str,str]], str]] = {
     "include":      cmd_include,
@@ -291,7 +298,9 @@ command2function:dict[str, Callable[[str, dict[str,str]], str]] = {
     "default":      cmd_default,
     "comment":      cmd_comment,
     "uncomment":    cmd_uncomment,
-    "sidenav":      Sidenav.cmd_sidenav
+    "sidenav":      Sidenav.cmd_sidenav,
+    "warning":      cmd_warning,
+    "error":        cmd_error,
 }
 
 """