diff --git a/brainunit/__init__.py b/brainunit/__init__.py
index fce3ee9..9880dd9 100644
--- a/brainunit/__init__.py
+++ b/brainunit/__init__.py
@@ -57,7 +57,6 @@ def set_default_magnitude(
   >>> set_default_magnitude(-9) # Alternatively, use an integer to represent the exponent of 10
   >>> set_default_magnitude({'m': -3, 'kg': -9}) # Set the default magnitude for 'metre' to 'milli' and 'kilogram' to 'nano'
   >>> set_default_magnitude({'m': 'm', 'kg': 'n'}) # Alternatively, use a string to represent the magnitude
-  >>> set_default_magnitude(-3, unit=volt) # Set the default magnitude for the 'volt' unit to 'milli'
   """
   global _default_magnitude
   if isinstance(magnitude, int):
@@ -102,4 +101,4 @@ def set_default_magnitude(
 
   global __all__
   __all__ = ['math'] + _common_all + _std_units_all + _constants_all + _base_all
-  del _common_all, _std_units_all, _constants_all, _base_all
\ No newline at end of file
+  del _common_all, _std_units_all, _constants_all, _base_all
diff --git a/brainunit/_unit_test.py b/brainunit/_unit_test.py
index 152b9f2..249f76a 100644
--- a/brainunit/_unit_test.py
+++ b/brainunit/_unit_test.py
@@ -1497,6 +1497,7 @@ def test_set_default_magnitude_1():
   assert q1.to_value() == 3e-3
   assert q2.to_value() == 3e-6
 
+
 def test_set_default_magnitude_2():
   bu.set_default_magnitude(-3)
   # from brainunit import second, ms, meter, kmeter
@@ -1522,6 +1523,7 @@ def test_set_default_magnitude_2():
   assert q1.to_value() == 3e-6
   assert q2.to_value() == 3e-6
 
+
 def test_set_default_magnitude_3():
   bu.set_default_magnitude({'s': 'm'})
   from brainunit import second, ms, meter, kmeter
@@ -1545,6 +1547,7 @@ def test_set_default_magnitude_3():
   assert q1.to_value() == 3e-3
   assert q2.to_value() == 3e-3
 
+
 def test_set_default_magnitude_4():
   # volt: m=2, kg=1, s=-3, A=-1
   bu.set_default_magnitude(-3)
@@ -1591,4 +1594,4 @@ def test_set_default_magnitude_4():
 #   q1 = 3 * volt
 #   q2 = 3 * mV
 #   assert q1.to_value() == 3e-3
-#   assert q2.to_value() == 3e-6
\ No newline at end of file
+#   assert q2.to_value() == 3e-6