diff --git a/pull_all.py b/pull_all.py
index 47a1737..64bd15a 100755
--- a/pull_all.py
+++ b/pull_all.py
@@ -1,3 +1,5 @@
+#!python3
+
 import os
 import sys
 
diff --git a/switch_git.py b/switch_git.py
new file mode 100755
index 0000000..0b590c0
--- /dev/null
+++ b/switch_git.py
@@ -0,0 +1,102 @@
+#!python3
+
+import os
+import sys
+import re
+import shutil
+
+path_done = set()
+
+
+def find_n_replace(git_path):
+    config_path = os.path.join(git_path, ".git/config")
+    subm_path = os.path.join(git_path, ".gitmodules")
+
+    with open(config_path, 'rt') as f:
+        of = open('config_new', 'wt')
+        for line in f:
+            if re.search(r'url\s*=(.*)192\.168\.100\.10', line):
+                print(line, end='')
+                newline = re.sub(r'192\.168\.100\.10', r'git.iluvatar.ai', line)
+                print(newline, end='')
+                of.write(newline)
+            else:
+                of.write(line)
+    of.close()
+    shutil.move('config_new', config_path)
+
+    if os.path.exists(subm_path) and os.path.isfile(subm_path) :
+        changed = False
+        with open(subm_path, 'rt') as f:
+            of = open('gitsubmodule_new', 'wt')
+            for line in f:
+                if re.search(r'url\s*=(.*)192\.168\.100\.10', line):
+                    print(line, end='')
+                    newline = re.sub(r'192\.168\.100\.10', r'git.iluvatar.ai', line)
+                    print(newline, end='')
+                    of.write(newline)
+                    changed = True
+                else:
+                    of.write(line)
+        of.close()
+        if changed:
+            shutil.move('gitsubmodule_new', subm_path)
+            print('    [!] Please commit your .gitmodules file')
+
+
+# copy from os.walk
+def walk(top, onerror=None, followlinks=False):
+    dirs = []
+    nondirs = []
+
+    try:
+        scandir_it = os.scandir(top)
+        entries = list(scandir_it)
+    except OSError as error:
+        if onerror is not None:
+            onerror(error)
+        return
+
+    for entry in entries:
+        try:
+            is_dir = entry.is_dir()
+        except OSError:
+            is_dir = False
+
+        if is_dir:
+            dirs.append(entry.name)
+        else:
+            nondirs.append(entry.name)
+
+    ############################################
+    # yield top, dirs, nondirs
+    if '.git' in dirs:
+        git_path = os.path.abspath(top)
+        path_done.add(git_path)
+        print("[GIT]", top)
+        find_n_replace(git_path)
+        return
+    else:
+        pass
+        #print("[PASS]", top)
+    ############################################
+
+    # Recurse into sub-directories
+    islink, join = os.path.islink, os.path.join
+    for dirname in dirs:
+        new_path = join(top, dirname)
+        if followlinks or not islink(new_path):
+            walk(new_path, onerror, followlinks)
+
+
+if __name__ == '__main__':
+    # deal with command line path
+    if len(sys.argv) > 1:
+        paths = sys.argv[1:]
+        script_path = sys.argv[0]
+    else:  # or use current directory as default
+        paths = ['.']
+
+    # iterate each top
+    for p in paths:
+        walk(p)
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