adding correct return type hint (#304)

src/dynode/covid_sero_initializer.py

@@ -8,7 +8,7 @@
 import numpy as np
 import pandas as pd
 
-from . import utils
+from . import SEIC_Compartments, utils
 from .abstract_initializer import AbstractInitializer
 from .config import Config
 
@@ -52,7 +52,9 @@ def __init__(self, config_initializer_path, global_variables_path):
             self.config.INITIAL_INFECTIONS
         )
 
-    def load_initial_state(self, initial_infections: float) -> None:
+    def load_initial_state(
+        self, initial_infections: float
+    ) -> SEIC_Compartments:
         """
         a function which takes a number of initial infections,
         disperses them across infectious and exposed compartments according to the INIT_INFECTED_DIST