diff --git a/minefield.py b/minefield.py
index b994ee7..014c0b8 100644
--- a/minefield.py
+++ b/minefield.py
@@ -26,15 +26,6 @@ mine_asset_options = {
 }
 
 
-def calculate_screen_position(row, column):
-    coords = (
-        const.V_SCREEN_PADDING + const.V_TILE_SIZE * column,
-        const.V_SCREEN_PADDING + const.V_TILE_SIZE * row,
-    )
-
-    return coords
-
-
 class Minefield:
     def __init__(self, json_path):
         self.turn = 0
@@ -66,13 +57,22 @@ class Minefield:
 
                 self.matrix[row][column].color = tile_data["color"].upper()
 
+    @staticmethod
+    def calculate_screen_position(row, column):
+        coords = (
+            const.V_SCREEN_PADDING + const.V_TILE_SIZE * column,
+            const.V_SCREEN_PADDING + const.V_TILE_SIZE * row,
+        )
+
+        return coords
+
     def draw(self, window):
         # iterate through tiles
         for row in self.matrix:
             for tile in row:
 
                 # calculate tile position on the screen
-                tile_screen_coords = calculate_screen_position(tile.position[0], tile.position[1])
+                tile_screen_coords = self.calculate_screen_position(tile.position[0], tile.position[1])
 
                 # draw a tile
                 window.blit(tile_asset_options.get(tile.color), tile_screen_coords)
@@ -84,7 +84,7 @@ class Minefield:
                     window.blit(mine_asset_options['A'], tile_screen_coords)
             
         # draw the sapper
-        sapper_screen_coords = calculate_screen_position(self.agent.position[0], self.agent.position[1])
+        sapper_screen_coords = self.calculate_screen_position(self.agent.position[0], self.agent.position[1])
         window.blit(const.ASSET_SAPPER, sapper_screen_coords)
 
     # ================ #
@@ -118,7 +118,7 @@ class Minefield:
         elif mine_type == "chained":
             if mine_data["predecessor"] is not None:
                 # locate predecessor
-                x, y = map(int, mine_data["predecessor"].split(','))
+                row, column = map(int, mine_data["predecessor"].split(','))
 
                 # get predecessor object and assign it to the new mine
                 predecessor = self.matrix[row][column].mine