Evaluate the time complexity of the following code snippets. Evaluate line by line, create a time complexity function and then define its Big O value.

a$.$

function sum$($arr$)\{$

counter $=0$

for $($i $=0$; i $<$ arr.length; i$++)\{$

counter $+=$ arr$[$i$]$

$\}$

return counter

$\}$