array fxns added: adding, subtracting, empty?, include?(<item>), .first and .last, .reverse, .map or .collect to alter elements, etc
intro to hashes
basic hash methods; how to access hashes within hashed, deleting, accessing, iterating through hashes; .keys, .values, .delete(key). hash.delete_if {|k,v| v > 25}
flow control stuff; need to get a better understanding of how to write methods to handle code blocks