In [1]:

    

def find_number(input_list, query):
    index=0
    index_list=[]
    for number in input_list:
        if number==query:
            index_list.append(index)
        index+=1
    if index_list:
        return index_list
    else:
        return 'Number not found'


    

In [2]:

    

l1=[1, 4, 5, 3, 6, 4, 7, 8, 3, 4, 5, 2]


    

In [3]:

    

find_number(l1, 4)


    

    
Out[3]:





[1, 5, 9]

In [4]:

    

find_number(l1, 0)


    

    
Out[4]:





'Number not found'

In [ ]: