Ruby - Array of hashes to keyed hash

hash.rb

students = [
  { name: "Bob", cohort: "Nov"},
  { name: "Barry", cohort: "Nov"},
  { name: "Anna", cohort: "Dec"},
  { name: "Igor", cohort: "Dec"},
  { name: "Natalia", cohort: "Feb"}
]

my_hash = {}

students.each { |student|
  cohort = student[:cohort]
  name = student[:name]

  # if the key exists then add to the array that already exists in the hash
  if (my_hash.has_key?(cohort))
    my_hash[cohort].push(name)
  else
    # the key doesnt exist so create an array and add it to the hash
    new_array = []
    new_array.push(name)
    my_hash[cohort] = new_array
  end
}

puts "My hash:"
puts my_hash

puts "Keys:"
puts my_hash.keys

puts "Loop through and display it:"
my_hash.keys.each { |cohort|
  print my_hash[cohort]
  puts
}

puts "Loop through each cohort as well to display students:"

my_hash.keys.each { |cohort|
  puts "Cohort: #{cohort}"
  my_hash[cohort].each { |student_name|
    puts "- #{student_name}"
  }
}