Histogram Area

Have the function HistogramArea $($arr$)$ read the

array of non$-$negative integers stored in arr which will

represent the heights of bars on a graph $($where each

bar width is $1),$ and determine the largest area

underneath the entire bar graph. For example: if arr is

$2,1,3,4,1$ then this looks like the following bar

graph:

You can see in the above bar graph that the largest

area underneath the graph is covered by the x$\text{'}$s$.$ The

area of that space is equal to $6$ because the entire

width is $2$ and the maximum height is $3,$ therefore $2**3$

$=6.$ Your program should return $6.$ The array will

always contain at least $1$

element.

give answer in python$3$