array = [5, 2, 8, -2, 10, 6, 1]

## using for loop 

def linear_search(arr, item):
    for n in arr:
        if n == item:
            return arr.index(n)
    return -1

print(linear_search(array, 8))
>> 2
print(linear_search(array, 7))
>> -1 


## using enumerate

def linear_search2(arr, item):
    for index, n in enumerate(arr):
        if n == item:
            return index
    return -1

print(linear_search2(array, 8))
>> 2
print(linear_search2(array, 7))
>> -1

## using range and len

def linear_search3(array, item):
    for n in range(len(array)):
        if array[n] == item:
            return n
    return -1

print(linear_search3(array, 8))
>> 2
print(linear_search3(array, 7))
>> -1