Answer:
def count_letters(text):
result = {}
# Go through each letter in the text
convert_text = text.lower()
for letter in convert_text:
if letter.isalpha():
if letter in result:
result[letter] += 1
else:
result[letter] = 1
return result
print(count_letters("AaBbCc"))
# Should be {'a': 2, 'b': 2, 'c': 2}
print(count_letters("Math is fun! 2+2=4"))
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}
print(count_letters("This is a sentence."))
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
Explanation: