Fix some mypy error

.flake8

@@ -0,0 +1,18 @@
+[flake8]
+extend-select = B9
+extend-ignore = E203, E231, E501, E722, W503, B950, B014, W504, E123, E126, E226, E121, B905, SIM113
+per-file-ignores = __init__.py:F401
+max-line-length = 120
+show-source = true
+exclude =
+    .git,
+    .idea,
+    .eggs,
+    __pycache__,
+    .tox,
+    docs/source/conf.py,
+    build,
+    .nox,
+    venv,
+    .venv
+application-import-names = mqt.qao

mypy.ini

@@ -0,0 +1,7 @@
+[mypy]
+# Specify the source directory
+mypy_path = src
+
+# Alternatively, you can use this to explicitly tell mypy to look in the src directory
+[mypy.src.*]
+ignore_missing_imports = True

pyproject.toml

@@ -111,7 +111,7 @@ filterwarnings = [
 ignore = "W002"
 
 [tool.coverage]
-run.source = ["mqt.predictor"]
+run.source = ["mqt.qao"]
 report.exclude_also = [
     '\.\.\.',
     'if TYPE_CHECKING:',
@@ -134,9 +134,6 @@ warn_unreachable = true
 explicit_package_bases = true
 pretty = true
 
-[[tool.mypy.overrides]]
-module = ["mqt.qao.*"]
-implicit_reexport = true
 
 [[tool.mypy.overrides]]
 module = ["qubovert.*", "sympy.*", "dwave.samplers.*", "dwave.system.*",  "docplex.*", "qiskit.*", "qiskit_optimization.*", "qiskit_ibm_provider.*", "matplotlib.*", "pandas.*", "pypfopt.*", "sklearn.*"]

src/mqt/qao/__init__.py

@@ -2,17 +2,19 @@
 
 import logging
 
-from src.mqt.qao.constraints import Constraints
-from src.mqt.qao.objectivefunction import ObjectiveFunction
-from src.mqt.qao.problem import Problem
-from src.mqt.qao.solvers import Solver
-from src.mqt.qao.variables import Variables
+from mqt.qao.constraints import Constraints
+from mqt.qao.objectivefunction import ObjectiveFunction
+from mqt.qao.problem import Problem
+from mqt.qao.solvers import Solution, Solver
+from mqt.qao.variables import Variable, Variables
 
 __all__ = [
+    "Variable",
     "Variables",
     "Constraints",
     "ObjectiveFunction",
     "Problem",
+    "Solution",
     "Solver",
 ]
 

src/mqt/qao/problem.py

@@ -6,7 +6,8 @@
 
 import numpy as np
 from qubovert import PUBO
-from src.mqt.qao import Constraints, ObjectiveFunction, Variables
+
+from mqt.qao import Constraints, ObjectiveFunction, Variables
 
 
 class Problem: