Ruby Array - Index, Part 1

def init_array()
    # create and return array with 10 elements ( integer ) in it
    # DO NOT EDIT THIS FUNCTION
    x = [9, 7, 6, 5, 4, 6, 7, 1, 2, 3]
    x
end
def element_at(arr, index)
    arr[index]
end

def inclusive_range(arr, start_pos, end_pos)
    arr[start_pos..end_pos]
end

def non_inclusive_range(arr, start_pos, end_pos)
    arr[start_pos...end_pos]
end

def start_and_length(arr, start_pos, length)
    arr[start_pos,length] 
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

ind = 8

val = element_at(arr, ind)

unless arr[ind] == element_at(arr, ind)
    x = val.to_s
    x = "nil" if val.nil?
    puts "Element at #{ind} returns #{x} is not #{arr[ind]}"
    exit(0)
else
    puts "Correct! Element at #{ind} is #{arr[ind]}!"
end

st = 4
en = 9

val = inclusive_range(arr, st, en)
unless arr[st..en] == val
    val = "nil" if val.nil?
    puts "The elements between the index #{st} and #{en} is #{arr[st..en]} and not #{val}"
    exit(0)
else
    puts "Correct! The elements between the index #{st} and #{en} is #{val}!"
end

st = 3
en = 8

val = non_inclusive_range(arr, st, en)
unless arr[st...en] == val
    val = "nil" if val.nil?
    puts "The elements between the index #{st} and #{en} (not included) is #{arr[st...en]} and not #{val}"
    exit(0)
else
    puts "Correct! The elements between the index #{st} and #{en} (not inclusive) is #{val}!"
end

st = 3
len = 6

val = start_and_length(arr, st, len)

unless arr[st, len] == val
    val = "nil" if val.nil?
    puts "The #{len} elements starting from #{st} are #{arr[st, len]} and not #{val}"
    exit(0)
else
    puts "Correct! The #{len} elements starting from #{st} are #{val}!"
end