def inexpensive
  ["a","b","c"]
end

def expensive
  sleep(1)
  ["a","b","c"]
end

puts "fast"
inexpensive.each do |item|
  puts item
end
puts "slow?"
expensive.each do |item|
  puts item
end

puts "will this run forever?"
myArr = ["a","b","c"]
myArr.each do |item|
  myArr.push("x")
end