def num_vowels(s):
    '''Return the number of vowels in string s.
    The letter "y" is not treated as a vowel.'''
			
    count = 0
    for char in s:
        if char in "aAeEiIoOuU":
            count = count + 1
				
    return count			

def remove_spaces(s):
    '''Return s with any spaces removed.'''

    s_no_spaces = ""
    for char in s:
       if char != " ":
           s_no_spaces += char

    return s_no_spaces

def count_matches(s1, s2):
    '''Return the number of chars in s1 that appear in s2.'''

    common_chars = 0
    for char in s1:
        if char in s2:
            common_chars += 1

    return common_chars

def grade(myAns,correctAnswer):
    if myAns == correctAnswer:
       print("Correct, the answer is",myAns)
    else:
       print("My answer is",myAns,"but the correct answer is",correctAnswer)

def main():

    #test them out
    grade(num_vowels('hello there fellow'), 6)
    grade(num_vowels('jjjddjsjsjd jjjj'), 0)
    grade(num_vowels(''),0)
    grade(num_vowels('a'),1)
    grade(num_vowels('b'),0)

    #test them out
    grade(remove_spaces('hello there fellow'),'hellotherefellow')
    grade(remove_spaces('jskrjeksuuyj'),'jskrjeksuuyj')
    grade(remove_spaces(''),'')
    grade(remove_spaces(' '),'')
    grade(remove_spaces(' b'),'b')    

    grade(count_matches("abcde","cdefg"),  3)
    grade(count_matches("abcde","fghij"),  0)
    grade(count_matches("abcde",''),  0)
    grade(count_matches('',''),  0)
    grade(count_matches('','abcde'),  0)            

    #now, let's write some code to reverse a list.  We won't create a function.
    #just to see that this is possible.
    s = 'abc'
    reverse = ""     # An accumulator
    for char in s:
        reverse = char + reverse
    grade(reverse,  'cba')

main()