diff --git a/src/Parser/__init__.py b/src/Parser/__init__.py
index c463b13..85b3742 100644
--- a/src/Parser/__init__.py
+++ b/src/Parser/__init__.py
@@ -1,6 +1,7 @@
-from typing import List, Tuple
+from typing import List, Tuple, Generator
 import arpeggio
 from itertools import chain
+from collections.abc import Mapping
 
 __all__ = ["js1_style", "js2_style"]
 
@@ -43,7 +44,7 @@ class ParseError(Exception):
         self.message = message
 
 
-class JobShopProblem(list):
+class JobShopProblem(Mapping):
 
     def __init__(
             self, jobs: int, machines: int,
@@ -59,11 +60,39 @@ class JobShopProblem(list):
         self.name = name
         self.machines = machines
         self.jobs = jobs
-        super().__init__(problem_data)
+        self.problem_data = problem_data
 
     def __str__(self) -> str:
         return "JobShopProblem " + str(self.name)
 
+    # make this behave like a mapping (e.g. a dict)
+    def __getitem__(self, key: Tuple[int, int]) -> Tuple[int, int]:
+        try:
+            # unpacking key
+            (jobnum, tasknum) = key
+            return self.problem_data[jobnum][tasknum]
+        except ValueError as e:
+            raise TypeError("Key must be a (int, int) tuple")
+
+    def __iter__(self):
+        self.iterpos1 = 0
+        self.iterpos2 = 0
+        return self
+
+    def __next__(self) -> Tuple[int, int]:
+        if self.iterpos1 >= len(self.problem_data):
+            raise StopIteration
+        return_key = (self.iterpos1, self.iterpos2)
+        self.iterpos2 += 1
+        if self.iterpos2 >= len(self.problem_data[self.iterpos1]):
+            self.iterpos2 = 0
+            self.iterpos1 += 1
+        return return_key
+
+
+    def __len__(self) -> int:
+        return sum(map(len, self.problem_data))
+
 
 class JobShopVisitor(arpeggio.PTNodeVisitor):
     """contains visitor functions needed for both jobshop1 (list of instances)
diff --git a/src/Parser/js1_style.py b/src/Parser/js1_style.py
index 1d4906e..6e5e81d 100644
--- a/src/Parser/js1_style.py
+++ b/src/Parser/js1_style.py
@@ -45,7 +45,7 @@ class JobShop1Visitor(JobShopVisitor):
         return None
 
 
-def parse_string(inputdata: str) -> JobShopProblem:
+def parse_string(inputdata: str) -> List[JobShopProblem]:
     """parse string with jobshop1-formatted data (multiple problem instances)
     and return list of JobShopProblem s"""
     parse_tree = parser.parse(inputdata)