'''
1.3 URLify
replace all spaces in a string with '%20'
'''

def URLify(input_str):
    return_str = ''
    for char in input_str:
        if char == ' ':
            return_str += '%20'
        else:
            return_str += char
    return return_str


print URLify('I have some spaces')
print URLify('nospacesnochange')
