class SyntaxTree::Parser

def on_when(arguments, statements, consequent)

) -> When
(nil | Else | When) consequent
Statements statements,
Args arguments,
on_when: (
:call-seq: 
def on_when(arguments, statements, consequent)
  beginning = consume_keyword(:when)
  ending = consequent || consume_keyword(:end)
  statements_start = arguments
  if (token = find_keyword(:then))
    tokens.delete(token)
    statements_start = token
  end
  start_char =
    find_next_statement_start((token || statements_start).location.end_char)
  statements.bind(
    self,
    start_char,
    start_char -
      line_counts[statements_start.location.start_line - 1].start,
    ending.location.start_char,
    ending.location.start_column
  )
  When.new(
    arguments: arguments,
    statements: statements,
    consequent: consequent,
    location: beginning.location.to(ending.location)
  )
end