diff --git a/exercises/ex12/cal b/exercises/ex12/cal
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+#!/usr/bin/env python
+# Exercise 12e
+# cal command
+
+import argparse
+import calendar
+from datetime import datetime
+
+calendar.setfirstweekday(calendar.SUNDAY)
+parser = argparse.ArgumentParser()
+parser.add_argument("-1", "--one", default=1, action="store_true")
+parser.add_argument("-3", "--three", default=False, action="store_true")
+parser.add_argument("-n", "--months", type=int)
+args = parser.parse_args()
+past = 3 if args.three else 0
+calendars = []
+
+
+def get_date(i):
+    year = datetime.now().year
+    month = datetime.now().month
+    tmp = month + i
+    if tmp < 1 or tmp > 12:
+        year += int(tmp / 12)
+        month = tmp % 12
+        if month == 0:
+            year -= 1
+            month = 12
+        if tmp < 1 and month < 12:
+            year -= 1
+    else:
+        month += i
+    return year, month
+
+
+for i in range(args.months or past or args.one):
+    if args.three:
+        i -= 1
+    year, month = get_date(i)
+    calendars.append(calendar.month(year, month))
+
+for i in range(2):
+    calendars.append("\n" * 8)
+
+for group in list(zip(*[iter(calendars)] * 3)):
+    group = list(map(lambda x: tuple(x.split("\n")), group))
+    group = list(zip(*group))
+    line_i = 0
+    for row in group:
+        line = ""
+        for col in row:
+            spaces = 20 - len(col)
+            line += col + "  " + (" " * spaces)
+        if len(line.strip()) > 0:
+            print(line)
+            line_i += 1
+    if line_i == 7 and len(calendars) - 2 > 3:
+        print()