simplify coord snap (#374)

dascore/core/coords.py

@@ -962,15 +962,9 @@ def snap(self):
             start, stop = max_v, min_v + step
         else:
             start, stop = min_v, max_v + step
-        # get potential output, ensure it is the same length as original
+        # Get potential output, ensure it is the same length as original.
         out = CoordRange(start=start, stop=stop, step=step, units=self.units)
-        # A hack to deal with those pesky off-by-one errors.
-        if out.shape != self.shape:
-            diff = len(self) - len(out)
-            new_stop = stop + diff * step  # increase or decrease coord length
-            out = out.update(stop=new_stop)
-        assert len(out) == len(self)
-        return out
+        return out.change_length(len(self))
 
     @compose_docstring(doc=BaseCoord.update_limits.__doc__)
     def update_limits(self, min=None, max=None, step=None, **kwargs) -> Self: