Getting acquaintance with 'def' in Python

RepeatingAlphabeth.py

alphabet = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
alphabetLength = len(alphabet)
	
def get_alphabet_till(length):
	# Validate input
	# 1) Check for type:
	if not (type(length) is int):	#type of length must be int
		return "Sorry, I expect int"
	# 2) Check range:
	if length > alphabetLength:		#length should be equal or less of letters count
		return "Sorry, there not so much letters in alphabet"
	result = ""
	for i in range(length):
		result += alphabet[i]
	return result	

def repeat_alphabet(howLong):
	# Validate input
	# Check for type:
	if not (type(howLong) is int):	#type of howLong must be int
		return "Sorry, I expect int"
	result = ""
	while howLong > 0:
		if howLong > alphabetLength:
			result += get_alphabet_till(alphabetLength)
		else:
			result += get_alphabet_till(howLong)
		howLong -= alphabetLength
	return result

print(repeat_alphabet(int(input("how many letters? "))))