class Holidays::Definition::Repository::CustomMethods

def add(new_custom_methods)

same ID already exists.
FIXME: this should probably return an error if a method with the

evidence of any current definitions that will cause an issue.
While this is not ideal I'm leaving it as-is since I have no
This performs a merge that overwrites any conflicts. 
def add(new_custom_methods)
  raise ArgumentError if new_custom_methods.nil?
  @custom_methods.merge!(new_custom_methods)
end

def find(method_id) 

def find(method_id)
  raise ArgumentError if method_id.nil? || method_id.empty?
  @custom_methods[method_id]
end

def initialize 

def initialize
  @custom_methods = {}
end