def linearSearch(arr,v):

    if arr == []:
        return False

    for i,x in enumerate(arr):
        if x == v:
            return i

    # if v in arr:
    #     return arr.index(v)

    return False

print(linearSearch([10,15,20,25,30],15))
print(linearSearch([9,8,7,6,5,4,3,2,1,0],4))
print(linearSearch([0],0))