Write a function called CountOccurences which takes two arguments.
The first is a single-character string and the second is a string of any length. The function should return the number of times that the character occurs in the second argument.
For example: CountOccurences(“a”,“Bananarama”) should return the integer 5.
For a challenge: add a third argument of type Boolean. If this argument is TRUE then the search is case-sensitive, if it is FALSE then the search ignores case. It should default to FALSE. If the language used by the centre allows it, this third argument could be optional – defaulting to TRUE.