style: split out the user list func

src/users.py

@@ -0,0 +1,36 @@
+import os
+
+def get_master():
+    ans = []
+    for year in os.listdir(f'/volume2/m3/master/'):
+        if os.path.isdir(f'/volume2/m3/master/{year}'):
+            for user in os.listdir(f'/volume2/m3/master/{year}'):
+                ans.append(f'/volume2/m3/master/{year}/{user}')
+    for user in os.listdir(f'/volume2/m3/master08'):
+        ans.append(f'/volume2/m3/master08/{user}')
+    for user in os.listdir(f'/volume2/m3/master09'):
+        ans.append(f'/volume2/m3/master09/{user}')
+    return ans
+
+def get_phd():
+    ans = []
+    for dir_name in os.listdir(f'/volume2/m3/phd/'):
+        if dir_name.isnumeric():
+            year = dir_name
+            for user in os.listdir(f'/volume2/m3/phd/{year}'):
+                ans.append(f'/volume2/m3/phd/{year}/{user}')
+        else:
+            ans.append(f'/volume2/m3/phd/{dir_name}')
+    return ans
+
+def get_ra():
+    ans = []
+    for user in os.listdir(f'/volume2/m3/ra/'):
+        ans.append(f'/volume2/m3/ra/{user}')
+    return ans
+
+def get_extra():
+    ans = []
+    for user in os.listdir(f'/volume2/m3/extra/'):
+        ans.append(f'/volume2/m3/extra/{user}')
+    return ans