quite a bit of development around get rates input handling

xexe/utils.py

@@ -0,0 +1,42 @@
+import datetime
+
+
+class DateRange:
+
+    def __init__(self, start_date: datetime.date, end_date: datetime.date):
+        if type(start_date) != datetime.date or type(end_date) != datetime.date:
+            raise TypeError("start_date and end_date must be date objects.")
+
+        if start_date > end_date:
+            raise ValueError("start_date can't be after end_date.")
+
+        self._start_date = start_date
+        self._end_date = end_date
+
+    @property
+    def start_date(self):
+        return self._start_date
+
+    @start_date.setter
+    def start_date(self, value: datetime.date):
+        if type(value) != datetime.date:
+            raise TypeError("start_date must be a date object.")
+
+        if value > self._end_date:
+            raise ValueError("start_date can't be after end_date.")
+
+        self._start_date = value
+
+    @property
+    def end_date(self):
+        return self._end_date
+
+    @end_date.setter
+    def end_date(self, value: datetime.date):
+        if type(value) != datetime.date:
+            raise TypeError("end_date must be a date object.")
+
+        if value < self._start_date:
+            raise ValueError("end_date can't be before start_date.")
+
+        self._end_date = value