Demonstrate elixir functions with different parameters

example.ex

defmodule Greeting do
  def say_hello do
    "Hello"
  end
  def say_hello(name) do
    "Hello #{name}"
  end
  def say_hello(name1, name2) do
    "Hello #{name1}, Hi #{name2}"
  end

end

IO.puts Greeting.say_hello() # Hello
IO.puts Greeting.say_hello("Bob") # Hello Bob
IO.puts Greeting.say_hello("Bob", "Bill") # Hello Bob, Hi Bill
IO.puts Greeting.say_hello("Bob", "Bill", "Billy") 
# (UndefinedFunctionError) function Greeting.say_hello/3 is undefined or private. Did you mean one of:
      * say_hello/0
      * say_hello/1
      * say_hello/2