class Concurrent::Map

def initialize(options = nil, &default_proc)

Parameters:

default_proc (Proc) -- Optional block to compute the default value if the key is not set, like `Hash#default_proc`
options (Hash, nil) -- options to set the :initial_capacity or :load_factor. Ignored on some Rubies.

def initialize(options = nil, &default_proc)
  if options.kind_of?(::Hash)
    validate_options_hash!(options)
  else
    options = nil
  end
  super(options)
  @default_proc = default_proc
end