Ruby Array - Index, Part 2

def init_array()
    # create and return array with 10 elements ( integer ) in it
    x = [9, 7, 6, 5, 4, 6, 7, 1, 2, 3]
    x
end
def neg_pos(arr, index)
    arr[-index]
end

def first_element(arr)
    arr.first  
end

def last_element(arr)
    arr.last
end

def first_n(arr, n)
    arr.take(n)
end

def drop_n(arr, n)
    arr.drop(n)
end

arr = init_array()

unless arr.is_a? Array
    puts "The variable returned from `init_array` is not an array"
    exit(0)
end

unless 10 == arr.length
    puts "Elements of the Array variable has to be exactly 10"
    exit(0)
else
    puts "Correct! Elements of the Array variable are 10 in number!"
end

unless arr.all? {|element| element.is_a? Integer}
    puts "All the elements of the Array initialized has to be integers"
    exit(0)
else
    puts "Correct! All the elements of the Array are Integers!"
end

neg_ind = 2
val = neg_pos(arr, neg_ind)
unless arr[-neg_ind] == val
    val = "nil" if val.nil?
    puts "The element at #{neg_ind} from the end of the array is not #{val}"
    exit(0)
else
    puts "Correct! The element at #{neg_ind} from the end of the array is #{val}"
end

val = first_element(arr)
unless arr.first == first_element(arr)
    val = "nil" if val.nil?
    puts "The first element of the array is not #{val}"
    exit(0)
else
    puts "Correct! The first element of the array is #{val}!"
end

val = last_element(arr)
unless arr.last == last_element(arr)
    val = "nil" if val.nil?
    puts "The last element of the array is not #{val}"
    exit(0)
else
    puts "Correct! The last element of the array is #{val}!"
end

len = 4
val = first_n(arr, len)
unless val == arr.take(len)
    val = "nil" if val.nil?
    puts "The first #{len} elements of the array are not #{val}"
    exit(0)
else
    puts "Correct! The first #{len} elements of the array are #{val}!"
end

len = 5
val = drop_n(arr, len)
unless val == arr.drop(len)
    val = "nil" if val.nil?
    puts "The elements of the array after dropping #{len} elements are not #{val}"
    exit(0)
else
    puts "Correct! The elements of the array after dropping #{len} elements are #{val}!"
end