TST, TYP: _use_dynamic_x

pandas/plotting/_matplotlib/timeseries.py

@@ -1,7 +1,7 @@
 # TODO: Use the fact that axis can have units to simplify the process
 
 import functools
-from typing import Optional
+from typing import TYPE_CHECKING, Optional
 
 import numpy as np
 
@@ -24,6 +24,10 @@
 from pandas.tseries.frequencies import is_subperiod, is_superperiod
 from pandas.tseries.offsets import DateOffset
 
+if TYPE_CHECKING:
+    from pandas._typing import FrameOrSeries  # noqa: F401
+
+
 # ---------------------------------------------------------------------
 # Plotting functions and monkey patches
 
@@ -188,7 +192,8 @@ def _get_freq(ax, series):
     return freq, ax_freq
 
 
-def _use_dynamic_x(ax, data):
+def _use_dynamic_x(ax, data: "FrameOrSeries") -> bool:
+
     freq = _get_index_freq(data)
     ax_freq = _get_ax_freq(ax)
 
@@ -203,9 +208,6 @@ def _use_dynamic_x(ax, data):
 
     freq = get_period_alias(freq)
 
-    if freq is None:
-        return False
-
     # FIXME: hack this for 0.10.1, creating more technical debt...sigh
     if isinstance(data.index, ABCDatetimeIndex):
         base = get_freq_code(freq)[0]