########
# Hash #
########
def function(opts)
  request = {}
  request[:name] = opts[:name] if opts[:name]
  request[:email] = opts[:email] if opts[:email]
  request[:address] = opts[:name] if opts[:name]
  post_to_service(request)
end

# Call it with:
function(name: "Bob", email: "test@foo.bar", address: "123 Fake St.")
function(name: "Bob", email: "test@foo.bar", address: nil)

################
# List of args #
################
def function(name, email = "bar@baz.qux", address = nil)
  request = {}
  request[:name] = name
  request[:email] = email
  request[:address] = address if address.present?
  post_to_service(request)
end

# Call it with
function(name = "Bob", email = "test@foo.bar", address = "123 Fake St.")
function(name = "Bob", email = "test@foo.bar")
function(name = "Bob")