class SyntaxTree::Parser

def on_unless(predicate, statements, consequent)

) -> UnlessNode
((nil | Elsif | Else) consequent)
Statements statements,
untyped predicate,
on_unless: (
:call-seq: 
def on_unless(predicate, statements, consequent)
  beginning = consume_keyword(:unless)
  ending = consequent || consume_keyword(:end)
  if (keyword = find_keyword_between(:then, predicate, ending))
    tokens.delete(keyword)
  end
  start_char =
    find_next_statement_start((keyword || predicate).location.end_char)
  statements.bind(
    self,
    start_char,
    start_char - line_counts[predicate.location.end_line - 1].start,
    ending.location.start_char,
    ending.location.start_column
  )
  UnlessNode.new(
    predicate: predicate,
    statements: statements,
    consequent: consequent,
    location: beginning.location.to(ending.location)
  )
end