add remove blanks in output

README.md

@@ -97,6 +97,19 @@ Same as `set`, but it returns the value of the variable that is being set. This
 ### default
 Same as `set`, but it sets the variable's value only if it has no value yet.
 
+### unset 
+Unset a variable
+
+**Synopsis**:
+Unset `varname`, it will no longer be defined and can therefor be set with `default` again.
+`<!-- #unset varname -->`
+
+**Argument**:
+Name of the variable
+
+**Return Value**:
+Empty string
+
 ---
 
 ### comment

html-preprocessor

@@ -273,7 +273,7 @@ def cmd_return(args: str, variables:dict[str, str]={}) -> str:
     # pdebug(f"cmd_set: varname='{args[:space]}, 'arg='{args[space+1:]}', variables='{variables}'")
     if not (space > 0 and space < len(args)-1):
         variables[args] = ""
-        pdebug(f"cmd_set: Setting to emptry string: {args}")
+        pdebug(f"cmd_set: Setting to empty string: {args}")
     else:
         varname = args[:space]
         variables[varname] = ""
@@ -308,6 +308,14 @@ def cmd_set(args: str, variables:dict[str, str]={}) -> str:
     cmd_return(args, variables)
     return ""
 
+def cmd_unset(args: str, variables:dict[str, str]={}) -> str:
+    variable = args.strip(' ')
+    if variable not in variables:
+        pdebug(f"unset: variable '{variable}' is not set", level=error_levels["light"])
+    else:
+        variables.pop(variable)
+    return ""
+
 def cmd_default(args: str, variables:dict[str, str]={}) -> str:
     separator = args.find(' ')
     if args[:separator] not in variables:
@@ -331,8 +339,9 @@ def cmd_warning(args: str, variables:dict[str, str]={}) -> str:
 command2function:dict[str, Callable[[str, dict[str,str]], str]] = {
     "include":      cmd_include,
     "section":      cmd_section,
-    "set":          cmd_set,
     "return":       cmd_return,
+    "set":          cmd_set,
+    "unset":        cmd_unset,
     "default":      cmd_default,
     "comment":      cmd_comment,
     "uncomment":    cmd_uncomment,
@@ -651,6 +660,8 @@ if __name__ == "__main__":
         target_html = file.read()
 
     output_html = parse_file(target_html, variables, not args.preserve_comments)
+    # remove empty lines
+    output_html = re.sub(r"[\t\r ]*\n(?:[\t\r ]*\n[\t\r ]*)+", r"\n", output_html)
 
     # pdebug(f"Output: {output_html}")