def acronomyze(string)
  # split our sentence on space
  string_split = string.split(" ")

  string_split.map do |word|
    word[0] # first letter of each string
  end

  # same as:
  # letters = []

  # string_split.each do |word|
  #   letters << word[0]
  # end

  # join our array into our string
  string_together = string_split.join

  # make the string uppercase
  string_together.upcase
end

puts acronomyze("Away From Keyboard") == "AFK"
puts acronomyze("Out of Offce") == "OOO"
puts acronomyze("") == ""
puts acronomyze("be right back") == "BRB"