Find the correct word by incrementing letters in alphabet

// Write a function that takes a string as argument
// As it is, the string has no meaning
// Increment each letter to the next letter in the alphabet
// Return the correct word
function
myFunction
(
str
)
{

return
}
Test Cases:
myFunction('bnchmf')
Expected
'coding'
myFunction('bgddrd')
Expected
'cheese'
myFunction('sdrshmf')
Expected
'testing'