diff --git a/QElephant/QuBit.py b/QElephant/QuBit.py
index 0a1be76..455510d 100644
--- a/QElephant/QuBit.py
+++ b/QElephant/QuBit.py
@@ -134,7 +134,7 @@ class MuBit:
         
         return prob
     
-    def __SWITCH(self, i: int) -> float:
+    def __SWITCH(self, i: int) -> None:
         if type(i) is not int:
             raise TypeError(f"MuBit indices must be integers, not {type(i)}")
         if i >= self.__n:
diff --git a/docs/QuBit/MuBit.md b/docs/QuBit/MuBit.md
index a22a68c..b0c586f 100644
--- a/docs/QuBit/MuBit.md
+++ b/docs/QuBit/MuBit.md
@@ -52,6 +52,10 @@ MuBit(n: int)
 
   returns the probability to get the i-th QuBit in the state |0>.
 
+- ```__SWITCH(i: int) -> None```
+
+  switches the i-th QuBit with the next one in __state.
+
 - ```observe() -> list[int]```
 
   forces the QuBits in a state, where the probabilities are given throught __state. Returns the list of the state of each QuBit.