use is true for bool var (#3973)

reflex/vars/sequence.py

@@ -194,14 +194,6 @@ class StringVar(Var[str]):
         """
         return string_strip_operation(self)
 
-    def bool(self):
-        """Boolean conversion.
-
-        Returns:
-            The boolean value of the string.
-        """
-        return self.length() != 0
-
     def reversed(self) -> StringVar:
         """Reverse the string.
 

tests/test_var.py

@@ -968,7 +968,7 @@ def test_all_number_operations():
     [
         (Var.create(False), "false"),
         (Var.create(True), "true"),
-        (Var.create("false"), '("false".split("").length !== 0)'),
+        (Var.create("false"), 'isTrue("false")'),
         (Var.create([1, 2, 3]), "isTrue([1, 2, 3])"),
         (Var.create({"a": 1, "b": 2}), 'isTrue(({ ["a"] : 1, ["b"] : 2 }))'),
         (Var("mysterious_var"), "isTrue(mysterious_var)"),