assertion keeps failing have attached my code:

method BadNbr$($a: array$)$ returns $($bn: int$)$

$\{$

if a$.$Length $<mtext></mtext><mn>2</mn><mtext></mtext><mi>\{</mi>$

return $-1$; $//$ No bad neighbors in arrays with fewer than $2$ elements

$\}$

var n :$=$ a$.$Length;

$//$ Check the wrap$-$around pair $($last and first elements$)$

if a$[$n $-1]+$ a$[0]<mtext></mtext><mn>0</mn><mtext></mtext><mi>\{</mi>$

return $0$; $//$ First element is a bad neighbor

$\}$

$//$ Check consecutive pairs in the array

var i :$=0$;

while i $$ n $-1\{$

if a$[$i$]+$ a$[$i $+1]<mtext></mtext><mn>0</mn><mtext></mtext><mi>\{</mi>$

return i $+1$; $//$ Found a bad neighbor

$\}$

i :$=$ i $+1$;

$\}$

return $-1$; $//$ No bad neighbors found

$\}$

method TestBadNbr$()\{$

$//$ Test case $1$: Empty array

var arr$1$ :$=$ new int$[0]$;

var res$1$ :$=$ BadNbr$($arr$1)$;

assert res$1==-1$;

$//$ Test case $2$: Array with one element

var arr$2$ :$=$ new int$[1]$;

arr$2[0]$ :$=5$;

var res$2$ :$=$ BadNbr$($arr$2)$;

assert res$2==-1$;

$//$ Test case $3$: Array with two elements where sum is negative

var arr$3$ :$=$ new int$[2]$;

arr$3[0]$ :$=1$;

arr$3[1]$ :$=-2$;

var res$3$ :$=$ BadNbr$($arr$3)$;

assert res$3==1$;

$//$ Test case $4$: Array with three elements and a bad neighbor pair

var arr$4$ :$=$ new int$[3]$;

arr$4[0]$ :$=3$;

arr$4[1]$ :$=-4$;

arr$4[2]$ :$=1$;

var res$4$ :$=$ BadNbr$($arr$4)$;

assert res$4==1$;

$//$ Test case $5$: Array with four elements and a wrap$-$around bad neighbor pair

var arr$5$ :$=$ new int$[4]$;

arr$5[0]$ :$=2$;

arr$5[1]$ :$=-1$;

arr$5[2]$ :$=3$;

arr$5[3]$ :$=-4$;

var res$5$ :$=$ BadNbr$($arr$5)$;

assert res$5==3$;

$//$ Additional test case: No bad neighbor

var arr$6$ :$=$ new int$[3]$;

arr$6[0]$ :$=3$;

arr$6[1]$ :$=2$;

arr$6[2]$ :$=1$;

var res$6$ :$=$ BadNbr$($arr$6)$;

assert res$6==-1$; $//$ No bad neighbors

$//$ Additional test case: Only wrap$-$around is a bad neighbor

var arr$7$ :$=$ new int$[4]$;

arr$7[0]$ :$=-1$;

arr$7[1]$ :$=2$;

arr$7[2]$ :$=3$;

arr$7[3]$ :$=-4$;

var res$7$ :$=$ BadNbr$($arr$7)$;

assert res$7==0$;

$\}$

rules:

All your solutions should verify, without warning or error, using Dafny version $4\mathrm{.}7.$ Assessment of the Dafny exercises takes into account efficiency, readability, conciseness and structure. $$ Use the language Dafny as presented in lectures. $$ Do not use language features from the Reference Manual, which includes function method, predicate method, assume or calc

and question:

In the first assignment a neighbour of an element in an array is simply an element next to the element in the array. Every element in an array longer than $1$ has in fact two neighbours: a neighbour on the left and another on the right. The first and last elements in an array are special cases that wrap$-$around clock$-$wise: the left neighbour of the first element is the last element in the array, and conversely the right neighbour of the last element is the first element in the array. In this exercise, if a neighbouring pair of element has a negative sum then the right neighbour is said to be bad. For example, the arrays $[0,-1],[-1,0]$ and $[0,0,-1]$ each has a negative$-$sum pair that wraps$-$around, so the neighbour on the right, which is index $0,$ is the bad neighbour. The array $[-1,0,1]$ has a negative$-$sum pair at indexes $0,1$ so index $1$ is the bad neighbour as it is on the right. The array $[2,-1,3,-2]$ does not contain a bad neighbour. If there is more than one bad neighbour then the element with the lowest index is the first bad neighbour. The array $[1,1,-2,-1]$ contains two bad index pairs, namely $1,2$ and $2,3,$ so the right neighbours in both, index $2$ and index $3,$ are bad. Index $2$ is therefore the first index that is bad. Write a verified method that returns the index of the first bad neighbour of an input array. The signature of the method should be: method BadNbr$($a: array$)$ returns $($bn:int$)$ where bn is the index of the first bad neighbour, or if there is no bad neighbour, bn$=-1.$ The array may be of any length. Validate that the method works correctly for a series of testcases. You may call your validator anything you like. Submit the file ex$1.$dfy$,$ which should contain method BadNbr and your validator. Notice Dafny method names use camel$-$notation, but filenames and Dafny predicate names are only lower$-$case.

please make sure the answer you give me is correct it is not fair I keep using expert solutions which I paid for and you don't give me the right answers