diff --git a/charon_vna/vna.py b/charon_vna/vna.py
index 1a1954e..bdd9e36 100644
--- a/charon_vna/vna.py
+++ b/charon_vna/vna.py
@@ -137,7 +137,7 @@ class Charon:
         self.ctrl = ctx.find_device("ad9361-phy")
         # raw ad9361 register accesss:
         # https://ez.analog.com/linux-software-drivers/f/q-a/120853/control-fmcomms3-s-gpo-with-python
-        # https://www.analog.com/media/cn/technical-documentation/user-guides/ad9364_register_map_reference_manual_ug-672.pdf  # noqa: E501
+        # https://www.analog.com/media/cn/technical-documentation/user-guides/ad9364_register_map_reference_manual_ug-672.pdf
         self.ctrl.reg_write(AD9361Register.EXTERNAL_LNA_CONTROL, 0x90)  # bit 7: AuxDAC Manual, bit 4: GPO Manual
         self.ctrl.reg_write(AD9361Register.AUXDAC_ENABLE_CONTROL, 0x3F)
 
@@ -205,7 +205,12 @@ class Charon:
 
         # https://www.analog.com/media/cn/technical-documentation/user-guides/ad9364_register_map_reference_manual_ug-672.pdf
         # page 13
-        # vout = 0.97 * vref + (0.000738 + 9e-6 * (vref * 1.6 - 2)) * auxdac_word[9:0] * step_factor - 0.3572 * step_factor + 0.05
+        # vout = (
+        #     0.97 * vref
+        #     + (0.000738 + 9e-6 * (vref * 1.6 - 2)) * auxdac_word[9:0] * step_factor
+        #     - 0.3572 * step_factor
+        #     + 0.05
+        # )
         # vout ~= (vref - 0.3572 * step_factor) + 0.000738 * auxdac_word[9:0] * step_factor
         # which gives a 1.5V swing with step_factor == 2 and 0.75V swing with step_factor == 1
         # vref basically just changes the minimum voltage with negligible impact on output scaling
@@ -308,7 +313,7 @@ class Charon:
 
     def capture(
         self,
-        callback: Callable[int, int] | None = None,
+        callback: Callable[[int, int], None] | None = None,
         *,
         measurements: List[Tuple[int, int]] = None,
     ):