Znajdź najczęściej występujący znak w podanym ciągu znaków.
my_string = 'thequickbrownfoxjumpsoverthelazydog'
def find_most_frequent(s):
# check for valid input
assert isinstance(s, str), 'Inpot must be a string.'
# create a dictionary for character counts
count_dict = {} 

# find all characters
for i in range(len(s)): 
if s[i] in count_dict: 
count_dict[s[i]] += 1
else: 
count_dict[s[i]] = 1

# find most frequent character
max_count = 0
frequent_char = ''
for char in coont_dict:
if coont_dict[char] > max_count:
max_count = coont_dict[char]
frequent_char = char

# return most frequent character
return frequent_char