join_strings.rb

def beep(a, b)
  result = ""
  result += a.to_s
  if a && b
    result += " and "
  end
  result += b.to_s
end

puts beep("foo", "bar")
puts beep("foo", nil)
puts beep(nil, "bar")

puts "---"

def boop(a, b)
  [a, b].compact.join(" and ")
end

puts boop("foo", "bar")
puts boop("foo", nil)
puts boop(nil, "bar")