diff --git a/.gitignore b/.gitignore
index 781a906..2ac0c77 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,5 @@ test.copapy
 token.txt
 /src/copapy/obj/*.o
 runmem2
+src/*.so
+bin/*
diff --git a/build.sh b/build.sh
index e759040..836ab23 100644
--- a/build.sh
+++ b/build.sh
@@ -9,5 +9,5 @@ gcc -c src/copapy/stencils.c -O2 -o src/copapy/obj/stencils_x86_64_O2.o
 gcc -c src/copapy/stencils.c -O3 -o src/copapy/obj/stencils_x86_64_O3.o
 
 mkdir bin -p
-gcc -Wall -Wextra -Wconversion -Wsign-conversion -Wshadow -Wstrict-overflow -Werror -g src/coparun/coparun.c src/coparun/runmem.c -o bin/coparun
+gcc -Wall -Wextra -Wconversion -Wsign-conversion -Wshadow -Wstrict-overflow -Werror -g src/coparun/runmem.c src/coparun/coparun.c -o bin/coparun
 #x86_64-w64-mingw32-gcc -Wall -Wextra -Wconversion -Wsign-conversion -Wshadow -Wstrict-overflow -Werror src/runner/runmem2.c -Wall -O3 -o bin/runmem2.exe
\ No newline at end of file
diff --git a/pyproject.toml b/pyproject.toml
index 0b32bc6..10ffc20 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -30,9 +30,6 @@ where = ["src"]
 [tool.setuptools.package-data]
 copapy = ["*.o"]
 
-[tool.setuptools.ext_modules]
-coparun = { sources = ["src/coparun/coparun_module.c"] }
-
 [project.optional-dependencies]
 dev = [
     "flake8",
diff --git a/setup.py b/setup.py
new file mode 100644
index 0000000..1618ae7
--- /dev/null
+++ b/setup.py
@@ -0,0 +1,13 @@
+from setuptools import setup, Extension
+
+ext = Extension(
+    "coparun_module",
+    sources=[
+        "src/coparun/coparun_module.c",
+        "src/coparun/runmem.c"
+    ]
+)
+
+setup(
+    ext_modules=[ext],
+)
diff --git a/src/copapy/__init__.py b/src/copapy/__init__.py
index 9bf8acb..a8d3a26 100644
--- a/src/copapy/__init__.py
+++ b/src/copapy/__init__.py
@@ -149,11 +149,11 @@ def stable_toposort(edges: Iterable[tuple[Node, Node]]) -> list[Node]:
     """Perform a stable topological sort on a directed acyclic graph (DAG).
     Arguments:
         edges: Iterable of (u, v) pairs meaning u -> v
-    
+
     Returns:
         List of nodes in topologically sorted order.
     """
-    
+
     # Track adjacency and indegrees
     adj: defaultdict[Node, list[Node]] = defaultdict(list)
     indeg: defaultdict[Node, int] = defaultdict(int)
@@ -163,9 +163,11 @@ def stable_toposort(edges: Iterable[tuple[Node, Node]]) -> list[Node]:
     pos = 0
     for u, v in edges:
         if u not in order:
-            order[u] = pos; pos += 1
+            order[u] = pos
+            pos += 1
         if v not in order:
-            order[v] = pos; pos += 1
+            order[v] = pos
+            pos += 1
         adj[u].append(v)
         indeg[v] += 1
         indeg.setdefault(u, 0)
@@ -254,7 +256,7 @@ def add_read_ops(node_list: list[Node]) -> Generator[tuple[Net | None, Node], No
 
 def add_write_ops(net_node_list: list[tuple[Net | None, Node]], const_nets: list[Net]) -> Generator[tuple[Net | None, Node], None, None]:
     """Add write operation for each new defined net if a read operation is later followed
-    
+
     Returns:
         Yields tuples of a net and a node. The associated net is provided for read and write nodes.
         Otherwise None is returned in the tuple.
@@ -306,7 +308,6 @@ def compile_to_instruction_list(end_nodes: Iterable[Node] | Node) -> binw.data_w
 
     # Get all nets associated with heap memory
     variable_list = get_nets([[const_net_list]], extended_output_ops)
-    assert(len(set(variable_list)) == len(variable_list)), 'Duplicates!'
 
     dw = binw.data_writer(sdb.byteorder)
 
diff --git a/src/copapy/binwrite.py b/src/copapy/binwrite.py
index 8db47e4..2740ac3 100644
--- a/src/copapy/binwrite.py
+++ b/src/copapy/binwrite.py
@@ -7,7 +7,7 @@ Command = Enum('Command', [('ALLOCATE_DATA', 1), ('COPY_DATA', 2),
                            ('ALLOCATE_CODE', 3), ('COPY_CODE', 4),
                            ('PATCH_FUNC', 5), ('PATCH_OBJECT', 6),
                            ('SET_ENTR_POINT', 64), ('READ_DATA', 65),
-                           ('END_PROG', 255)])
+                           ('END_PROG', 256), ('FREE_MEMORY', 257)])
 
 
 class data_writer():
diff --git a/src/copapy/generate_stencils.py b/src/copapy/generate_stencils.py
index 7e975e9..65191ee 100644
--- a/src/copapy/generate_stencils.py
+++ b/src/copapy/generate_stencils.py
@@ -7,7 +7,7 @@ op_signs = {'add': '+', 'sub': '-', 'mul': '*', 'div': '/'}
 def get_function_start() -> str:
     return """
     int function_start(){
-        result_int(0);  // dummy call instruction before marker gets striped 
+        result_int(0);  // dummy call instruction before marker gets striped
         asm volatile (".long 0xF27ECAFE");
         return 1;
     }
diff --git a/src/copapy/stencils.c b/src/copapy/stencils.c
index 9f7fb56..76cf938 100644
--- a/src/copapy/stencils.c
+++ b/src/copapy/stencils.c
@@ -224,7 +224,7 @@
     }
     
     int function_start(){
-        result_int(0);  // dummy call instruction before marker gets striped 
+        result_int(0);  // dummy call instruction before marker gets striped
         asm volatile (".long 0xF27ECAFE");
         return 1;
     }
diff --git a/src/coparun/coparun.c b/src/coparun/coparun.c
index e69de29..dfb8331 100644
--- a/src/coparun/coparun.c
+++ b/src/coparun/coparun.c
@@ -0,0 +1,52 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include "runmem.h"
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <binary_file>\n", argv[0]);
+        return EXIT_FAILURE;
+    }
+
+    // Open the file
+    int fd = open(argv[1], O_RDONLY);
+    if (fd < 0) {
+        perror("open");
+        return EXIT_FAILURE;
+    }
+
+    // Get file size
+    struct stat st;
+    if (fstat(fd, &st) < 0) {
+        perror("fstat");
+        close(fd);
+        return EXIT_FAILURE;
+    }
+
+    if (st.st_size == 0) {
+        fprintf(stderr, "Error: File is empty\n");
+        close(fd);
+        return EXIT_FAILURE;
+    }
+
+    //uint8_t *file_buff = get_data_memory((uint32_t)st.st_size);
+    uint8_t *file_buff = (uint8_t*)malloc((size_t)st.st_size);
+
+    // Read file into allocated memory
+    if (read(fd, file_buff, (long unsigned int)st.st_size) != st.st_size) {
+        perror("read");
+        close(fd);
+        return EXIT_FAILURE;
+    }
+    close(fd);
+
+    parse_commands(file_buff);
+
+    free_memory();
+
+    return EXIT_SUCCESS;
+}
diff --git a/src/coparun/coparun_module.c b/src/coparun/coparun_module.c
index 99f1535..735f573 100644
--- a/src/coparun/coparun_module.c
+++ b/src/coparun/coparun_module.c
@@ -1,31 +1,46 @@
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
+#include "runmem.h"
 
-// A simple C function exposed to Python
-static PyObject* my_function(PyObject* self, PyObject* args) {
-    int a, b;
-    if (!PyArg_ParseTuple(args, "ii", &a, &b)) {
-        return NULL;  // Error if arguments aren't two integers
+/*
+ * coparun(PyObject *self, PyObject *args)
+ * Accepts a Python `bytes` (or objects supporting the buffer protocol).
+ * We use the "y#" format in PyArg_ParseTuple which returns a pointer to
+ * the internal bytes buffer and its length (Py_ssize_t). For safety and
+ * performance we pass that pointer directly to parse_commands which expects
+ * a uint8_t* buffer. If parse_commands needs the length, consider
+ * extending its API to accept a length parameter.
+ */
+static PyObject* coparun(PyObject* self, PyObject* args) {
+    const char *buf;
+    Py_ssize_t buf_len;
+    int result;
+
+    if (!PyArg_ParseTuple(args, "y#", &buf, &buf_len)) {
+        return NULL; /* TypeError set by PyArg_ParseTuple */
     }
-    return PyLong_FromLong(a + b);  // Return sum as Python integer
+
+    /* If parse_commands may run for a long time, release the GIL. */
+    Py_BEGIN_ALLOW_THREADS
+    result = parse_commands((uint8_t*)buf);
+    Py_END_ALLOW_THREADS
+
+    return PyLong_FromLong(result);
 }
 
-// Method definitions
 static PyMethodDef MyMethods[] = {
-    {"add", my_function, METH_VARARGS, "Adds two numbers"},
-    {NULL, NULL, 0, NULL}  // Sentinel
+    {"coparun", coparun, METH_VARARGS, "Pass raw command data to coparun"},
+    {NULL, NULL, 0, NULL}
 };
 
-// Module definition
-static struct PyModuleDef my_module = {
+static struct PyModuleDef coparun_module = {
     PyModuleDef_HEAD_INIT,
-    "my_module",  // Module name
+    "coparun_module",  // Module name
     NULL,         // Documentation
     -1,           // Size of per-interpreter state (-1 for global)
     MyMethods
 };
 
-// Module initialization function
-PyMODINIT_FUNC PyInit_my_module(void) {
-    return PyModule_Create(&my_module);
+PyMODINIT_FUNC PyInit_coparun_module(void) {
+    return PyModule_Create(&coparun_module);
 }
\ No newline at end of file
diff --git a/src/coparun/runmem.c b/src/coparun/runmem.c
index a6995ca..ebca06d 100644
--- a/src/coparun/runmem.c
+++ b/src/coparun/runmem.c
@@ -6,23 +6,14 @@
 #include <sys/stat.h>
 #include <string.h>
 #include <stdint.h>
+#include "runmem.h"
 
-#define ALLOCATE_DATA 1
-#define COPY_DATA 2
-#define ALLOCATE_CODE 3
-#define COPY_CODE 4
-#define PATCH_FUNC 5
-#define PATCH_OBJECT 6
-#define SET_ENTR_POINT 64
-#define READ_DATA 65
-#define END_PROG 255
-
-#define PATCH_RELATIVE_32 0
-
-uint8_t *data_memory;
-uint8_t *executable_memory;
-uint32_t executable_memory_len;
-int (*entr_point)();
+/* Definitions for globals declared extern in runmem.h */
+uint8_t *data_memory = NULL;
+uint32_t data_memory_len = 0;
+uint8_t *executable_memory = NULL;
+uint32_t executable_memory_len = 0;
+entry_point_t entr_point = NULL;
 
 uint8_t *get_executable_memory(uint32_t num_bytes){
     // Allocate executable memory
@@ -62,7 +53,14 @@ int patch(uint8_t *patch_addr, uint32_t reloc_type, int32_t value){
         return 0;
     }
     return 1;
-}  
+}
+
+void free_memory(){
+    if (executable_memory_len) munmap(executable_memory, executable_memory_len);
+    if (data_memory_len) munmap(data_memory, data_memory_len);
+    data_memory_len = 0;
+    executable_memory_len = 0;
+}
 
 int parse_commands(uint8_t *bytes){
     int32_t value;
@@ -78,9 +76,15 @@ int parse_commands(uint8_t *bytes){
         command = *(uint32_t*)bytes;
         bytes += 4;
         switch(command) {
+            case FREE_MEMORY:
+                size = *(uint32_t*)bytes; bytes += 4;
+                free_memory();
+                break;
+
         	case ALLOCATE_DATA:
                 size = *(uint32_t*)bytes; bytes += 4;
                 data_memory = get_data_memory(size);
+                data_memory_len = size;
                 printf("ALLOCATE_DATA size=%i mem_addr=%p\n", size, (void*)data_memory);
                 break;
             
@@ -163,47 +167,3 @@ int parse_commands(uint8_t *bytes){
     }
     return err_flag;
 }
-
-int main(int argc, char *argv[]) {
-    if (argc != 2) {
-        fprintf(stderr, "Usage: %s <binary_file>\n", argv[0]);
-        return EXIT_FAILURE;
-    }
-
-    // Open the file
-    int fd = open(argv[1], O_RDONLY);
-    if (fd < 0) {
-        perror("open");
-        return EXIT_FAILURE;
-    }
-
-    // Get file size
-    struct stat st;
-    if (fstat(fd, &st) < 0) {
-        perror("fstat");
-        close(fd);
-        return EXIT_FAILURE;
-    }
-
-    if (st.st_size == 0) {
-        fprintf(stderr, "Error: File is empty\n");
-        close(fd);
-        return EXIT_FAILURE;
-    }
-
-    //uint8_t *file_buff = get_data_memory((uint32_t)st.st_size);
-    uint8_t *file_buff = (uint8_t*)malloc((size_t)st.st_size);
-
-    // Read file into allocated memory
-    if (read(fd, file_buff, (long unsigned int)st.st_size) != st.st_size) {
-        perror("read");
-        close(fd);
-        return EXIT_FAILURE;
-    }
-    close(fd);
-
-    parse_commands(file_buff);
-
-    munmap(executable_memory, executable_memory_len);
-    return EXIT_SUCCESS;
-}
diff --git a/src/coparun/runmem.h b/src/coparun/runmem.h
index e69de29..77b7bd6 100644
--- a/src/coparun/runmem.h
+++ b/src/coparun/runmem.h
@@ -0,0 +1,39 @@
+#ifndef RUNMEM_H
+#define RUNMEM_H
+
+#include <stdint.h>
+
+/* Command opcodes used by the parser */
+#define ALLOCATE_DATA    1
+#define COPY_DATA        2
+#define ALLOCATE_CODE    3
+#define COPY_CODE        4
+#define PATCH_FUNC       5
+#define PATCH_OBJECT     6
+#define SET_ENTR_POINT   64
+#define READ_DATA        65
+#define END_PROG         256
+#define FREE_MEMORY      257
+
+/* Relocation types */
+#define PATCH_RELATIVE_32 0
+
+/* Memory blobs accessible by other translation units */
+extern uint8_t *data_memory;
+extern uint32_t data_memory_len;
+extern uint8_t *executable_memory;
+extern uint32_t executable_memory_len;
+
+/* Entry point type and variable */
+typedef int (*entry_point_t)(void);
+extern entry_point_t entr_point;
+
+
+/* Command parser: takes a pointer to the command stream and returns
+   an error flag (0 on success according to current code) */
+int parse_commands(uint8_t *bytes);
+
+/* Free program and data memory */
+void free_memory();
+
+#endif /* RUNMEM_H */
\ No newline at end of file
diff --git a/tests/test_ast_gen.py b/tests/test_ast_gen.py
index 977409c..bc30bc3 100644
--- a/tests/test_ast_gen.py
+++ b/tests/test_ast_gen.py
@@ -1,6 +1,5 @@
-from copapy import Write, const, Node
+from copapy import Write, const
 import copapy as rc
-from typing import Iterable, Generator
 
 
 def test_ast_generation():
diff --git a/tests/test_compile.py b/tests/test_compile.py
index 4d7541e..6c39bf6 100644
--- a/tests/test_compile.py
+++ b/tests/test_compile.py
@@ -2,7 +2,7 @@ from copapy import Write, const
 import copapy
 import subprocess
 import struct
-from copapy import binwrite as binw
+from copapy import binwrite
 
 
 def run_command(command: list[str], encoding: str = 'utf8') -> str:
@@ -60,12 +60,12 @@ def test_compile():
     copapy.read_variable(il, r1)
     copapy.read_variable(il, r2)
 
-    il.write_com(binw.Command.READ_DATA)
+    il.write_com(binwrite.Command.READ_DATA)
     il.write_int(0)
     il.write_int(36)
 
     # run program command
-    il.write_com(binw.Command.END_PROG)
+    il.write_com(binwrite.Command.END_PROG)
 
     print('* Data to runner:')
     il.print()
diff --git a/tests/test_coparun_module.py b/tests/test_coparun_module.py
new file mode 100644
index 0000000..b081f2c
--- /dev/null
+++ b/tests/test_coparun_module.py
@@ -0,0 +1,39 @@
+from coparun_module import coparun
+from copapy import Write, const
+import copapy
+from copapy import binwrite
+
+
+def test_compile():
+
+    c1 = const(4)
+    c2 = const(2)
+
+    i1 = c1 * 2
+    r1 = i1 + 7 + (c2 + 7 * 9)
+    r2 = i1 + 9
+    out = [Write(r1), Write(r2)]
+
+    il = copapy.compile_to_instruction_list(out)
+
+    copapy.read_variable(il, r1)
+    copapy.read_variable(il, r2)
+
+    il.write_com(binwrite.Command.READ_DATA)
+    il.write_int(0)
+    il.write_int(36)
+
+    # run program command
+    il.write_com(binwrite.Command.END_PROG)
+
+    #print('* Data to runner:')
+    #il.print()
+
+    print('+ run coparun')
+    result = coparun(il.get_data())
+
+    assert result == 1
+
+
+if __name__ == "__main__":
+    test_compile()