module Jekyll::Utils

def parse_date(input, msg = "Input could not be parsed.")

if not
Returns the parsed date if successful, throws a FatalException

msg - (optional) the error message to show the user
input - the date/time to parse

Parse a date/time and throw an error if invalid 
def parse_date(input, msg = "Input could not be parsed.")
  @parse_date_cache ||= {}
  @parse_date_cache[input] ||= Time.parse(input).localtime
rescue ArgumentError
  raise Errors::InvalidDateError, "Invalid date '#{input}': #{msg}"
end