qapi: Drop Indentation.__bool__()

Intentation.__bool__() is not worth its keep: it has just one user,
which can just as well check .__str__() instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210908045428.2689093-3-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

scripts/qapi/common.py

@@ -142,10 +142,6 @@ def __str__(self) -> str:
         """Return the current indentation as a string of spaces."""
         return ' ' * self._level
 
-    def __bool__(self) -> bool:
-        """True when there is a non-zero indentation."""
-        return bool(self._level)
-
     def increase(self, amount: int = 4) -> None:
         """Increase the indentation level by ``amount``, default 4."""
         self._level += amount
@@ -169,8 +165,9 @@ def cgen(code: str, **kwds: object) -> str:
     Obey `indent`, and strip `EATSPACE`.
     """
     raw = code % kwds
-    if indent:
-        raw = re.sub(r'^(?!(#|$))', str(indent), raw, flags=re.MULTILINE)
+    pfx = str(indent)
+    if pfx:
+        raw = re.sub(r'^(?!(#|$))', pfx, raw, flags=re.MULTILINE)
     return re.sub(re.escape(EATSPACE) + r' *', '', raw)