diff --git a/sbysrc/win_killpg.py b/sbysrc/win_killpg.py
deleted file mode 100644
index 364e175..0000000
--- a/sbysrc/win_killpg.py
+++ /dev/null
@@ -1,88 +0,0 @@
-from ctypes import sizeof, windll
-from ctypes.wintypes import DWORD, LONG, ULONG
-from ctypes import Structure, c_char, pointer, POINTER
-import os
-
-# relevant WinAPI references:
-# https://docs.microsoft.com/en-us/windows/win32/api/tlhelp32/nf-tlhelp32-createtoolhelp32snapshot
-# https://docs.microsoft.com/en-us/windows/win32/api/tlhelp32/ns-tlhelp32-processentry32
-# https://docs.microsoft.com/en-us/windows/win32/api/tlhelp32/nf-tlhelp32-process32first
-# https://docs.microsoft.com/en-us/windows/win32/api/tlhelp32/nf-tlhelp32-process32next
-
-TH32CS_SNAPPROCESS = 0x00000002
-INVALID_HANDLE_VALUE = -1
-
-
-class PROCESSENTRY32(Structure):
-    _fields_ = [
-        ("dwSize", DWORD),
-        ("cntUsage", DWORD),
-        ("th32ProcessID", DWORD),
-        ("th32DefaultHeapID", POINTER(ULONG)),
-        ("th32ModuleID", DWORD),
-        ("cntThreads", DWORD),
-        ("th32ParentProcessID", DWORD),
-        ("pcPriClassBase", LONG),
-        ("dwFlags", DWORD),
-        ("szExeFile", c_char * 260),
-    ]
-
-
-def _visit_all_children(pid, lookup, visited):
-    if pid not in visited:
-        visited.add(pid)
-        if pid in lookup:
-            for c in lookup[pid]:
-                _visit_all_children(c, lookup, visited)
-
-
-def _update_lookup(pid_lookup, pe):
-    cpid = pe.contents.th32ProcessID
-    ppid = pe.contents.th32ParentProcessID
-    # pid 0 should be the only one that is its own parent.
-    # don't add this entry to the graph to avoid an unwanted cycle
-    if ppid == 0 and cpid == 0:
-        return
-    assert (
-        cpid != ppid
-    ), "Internal error listing windows processes - process is its own parent"
-    if ppid not in pid_lookup:
-        pid_lookup[ppid] = []
-    pid_lookup[ppid].append(cpid)
-
-
-def _create_process_lookup():
-    handle = windll.kernel32.CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
-    if handle == INVALID_HANDLE_VALUE:
-        raise RuntimeError(
-            "Could not snapshot running processes - invalid handle returned"
-        )
-    pe = pointer(PROCESSENTRY32())
-    pe.contents.dwSize = sizeof(PROCESSENTRY32)
-    pid_lookup = {}
-    if windll.kernel32.Process32First(handle, pe) != 0:
-        _update_lookup(pid_lookup, pe)
-        while windll.kernel32.Process32Next(handle, pe) != 0:
-            _update_lookup(pid_lookup, pe)
-
-    return pid_lookup
-
-
-def win_killpg(pid):
-    """
-    Approximate the behaviour of os.killpg(pid, signal.SIGKILL) on Windows.
-
-    Windows processes appear to keep track of their parent rather than their
-    children, so it is necessary to build a graph of all running processes
-    first and use this to derive a list of child processes to be killed.
-    """
-    pid_lookup = _create_process_lookup()
-    to_kill = set()
-    _visit_all_children(pid, pid_lookup, to_kill)
-    for p in to_kill:
-        try:
-            # "Any other value for sig will cause the process to be
-            # unconditionally killed by the TerminateProcess API"
-            os.kill(p, -1)
-        except (PermissionError, OSError) as e:
-            print("WARNING: error while killing pid {}: {}".format(p, e))