class Date

+:monday+, +:tuesday+, +:wednesday+, +:thursday+, +:friday+, +:saturday+, +:sunday+
This method accepts any of the following day symbols:

Sets Date.beginning_of_week to a week start (e.g. +:monday+) for current request/thread.

def beginning_of_week=(week_start)
  ::ActiveSupport::IsolatedExecutionState[:beginning_of_week] = find_beginning_of_week!(week_start)
end