To delete none after using def statement in Python

n = input('Enter string:')
n = n.lower()
n = n.replace(' ','')
n = n.replace('',' ')
n = n.strip()
L = n.split(' ')
S = set(L)
X = list(S)
k = len(X)
def moonchk(n) :
    for i in range(0,k):
        a = X[i]
        print(a, ':', L.count(a))
    return ''
print(moonchk(n))