diff --git a/assignment_collection/simplifications.py b/assignment_collection/simplifications.py
index f8b2b23adb0809bfade757bf1d94b1cf4fd0426c..5c8a13f98cef1ecd1f3a838752d9a214a969fb7d 100644
--- a/assignment_collection/simplifications.py
+++ b/assignment_collection/simplifications.py
@@ -29,7 +29,7 @@ def sympy_cse(ac: AssignmentCollection) -> AssignmentCollection:
 
 def sympy_cse_on_assignment_list(assignments: List[Assignment]) -> List[Assignment]:
     """Extracts common subexpressions from a list of assignments."""
-    ec = AssignmentCollection(assignments, [])
+    ec = AssignmentCollection([], assignments)
     return sympy_cse(ec).all_assignments
 
 
diff --git a/backends/cbackend.py b/backends/cbackend.py
index c2806f9e701f706ebdb0bf785c2b9b82e79b171a..64c863fb41d2a63badf1cf234b01cd1b9d28efa2 100644
--- a/backends/cbackend.py
+++ b/backends/cbackend.py
@@ -13,7 +13,7 @@ from pystencils.astnodes import Node, ResolvedFieldAccess, SympyAssignment
 from pystencils.data_types import create_type, PointerType, get_type_of_expression, VectorType, cast_func
 from pystencils.backends.simd_instruction_sets import selectedInstructionSet
 
-__all__ = ['generate_c', 'CustomCppCode', 'get_headers']
+__all__ = ['generate_c', 'CustomCppCode', 'PrintNode', 'get_headers']
 
 
 def generate_c(ast_node: Node, signature_only: bool = False, use_float_constants: Optional[bool] = None) -> str:
diff --git a/qtgui.py b/qtgui.py
deleted file mode 100644
index 2ce9cfa59ad8d399c2242cb770a6cfb695282130..0000000000000000000000000000000000000000
--- a/qtgui.py
+++ /dev/null
@@ -1,48 +0,0 @@
-import sys
-from PyQt5.QtWidgets import QWidget, QApplication, QTreeWidget, QTreeWidgetItem, QHBoxLayout
-from pystencils.astnodes import Block, LoopOverCoordinate, KernelFunction
-
-
-def debug_gui(ast):
-    app = QApplication.instance()
-    if app is None:
-        app = QApplication(sys.argv)
-    else:
-        print('QApplication instance already exists: %s' % str(app))
-    ex = DebugTree()
-    ex.insert_ast(ast)
-    app.exec_()
-
-
-class DebugTree(QWidget):
-    def __init__(self):
-        super().__init__()
-        self.initUI()
-
-    def initUI(self):
-        self.tree = QTreeWidget(self)
-        self.tree.setColumnCount(1)
-        self.tree.setHeaderLabel('repr')
-
-        hbox = QHBoxLayout()
-        hbox.stretch(1)
-        hbox.addWidget(self.tree)
-
-        self.setWindowTitle('Debug')
-        self.setLayout(hbox)
-        self.show()
-
-    def insert_ast(self, node, parent=None):
-        if parent is None:
-            parent = self.tree
-        if isinstance(node, Block):  # Blocks are represented with the tree structure
-            item = parent
-        else:
-            item = QTreeWidgetItem(parent)
-            item.setText(0, repr(node))
-
-        if node.func in [LoopOverCoordinate, KernelFunction]:
-            self.tree.expandItem(item)
-
-        for child in node.args:
-            self.insert_ast(child, item)