// your code goes here
 
const increasingSequence = (arr) => !arr.some((val, idx) => val != arr[0] + idx);
 
var arr1 = [1, 2, 3, 4];
var arr2 = [1, 2, 4, 5];
var arr3 = [-4, -3, -2, -1];
var arr4 = [-4, -3, -1, 0];
var arr5 = [4, 3, 2, 1, 0];
 
print(increasingSequence(arr1)); // true
print(increasingSequence(arr2)); // false
print(increasingSequence(arr3)); // true
print(increasingSequence(arr4)); // false
print(increasingSequence(arr5)); // false
 

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