class SyntaxTree::Parser

def on_while_mod(predicate, statement)

on_while_mod: (untyped predicate, untyped statement) -> WhileNode
:call-seq: 
def on_while_mod(predicate, statement)
  consume_keyword(:while)
  WhileNode.new(
    predicate: predicate,
    statements:
      Statements.new(body: [statement], location: statement.location),
    location: statement.location.to(predicate.location)
  )
end