Using Python 3, I need a function that takes as a parameter a string and returns a dictionary that tabulates how many of each letter is in that string and does not count spaces. The string should contain characters other than letters, but it will only count the letters(it will not count numbers or spaces). The string could even be the empty string (just ""). Lower-case and upper-case versions of a letter should be part of the same count. The keys of the dictionary should be upper-case letters. If a letter does not appear in the string, then it would not get added to the dictionary. If the string is: "AaBb278"
then the dictionary that is returned should contain these key-value pairs:

{'A': 2, 'B': 2}
Do not use the isalpha() funciton, the collection method or the import method.