from collections import defaultdict

def collect_dictionary(obj):
  inv_obj = defaultdict(list)
  for key, value in obj.items():
    inv_obj[value].append(key)
  return dict(inv_obj)
  
ages = {
  'Peter': 10,
  'Isabel': 10,
  'Anna': 9,
}
collect_dictionary(ages) # { 10: ['Peter', 'Isabel'], 9: ['Anna'] }

from math import pi

def rads_to_degrees(rad):
  return (rad * 180.0) / pi

rads_to_degrees(pi / 2) # 90.0

# function which return reverse of a string
def isPalindrome(s):
    return s == s[::-1]
 
# Driver code
s = "malayalam"
ans = isPalindrome(s)
 
if ans:
    print("Yes")
else:
    print("No")

import calendar

# Prompt user for year and month
year = int(input("Enter the year: "))
month = int(input("Enter the month: "))

# Create a calendar object
cal = calendar.monthcalendar(year, month)

# Display the calendar
print(calendar.month_name[month], year)
print("Mon  Tue  Wed  Thu  Fri  Sat  Sun")

for week in cal:
    for day in week:
        if day == 0:
            print("     ", end="")
        else:
            print(str(day).rjust(2), "  ", end="")
    print()

def max_n(lst, n = 1):
  return sorted(lst, reverse = True)[:n]

max_n([1, 2, 3]) # [3]
max_n([1, 2, 3], 2) # [3, 2]

def when(predicate, when_true):
  return lambda x: when_true(x) if predicate(x) else x

double_even_numbers = when(lambda x: x % 2 == 0, lambda x : x * 2)
print(double_even_numbers(2)) # 4
print(double_even_numbers(1)) # 1