class ActionDispatch::Journey::GTG::TransitionTable

def []=(from, to, sym)
  to_mappings = states_hash_for(sym)[from] ||= {}
  case sym
  when Regexp
    # we must match the whole string to a token boundary
    if sym == DEFAULT_EXP
      sym = DEFAULT_EXP_ANCHORED
    else
      sym = /\A#{sym}\Z/
    end
  when Symbol
    # account for symbols in the constraints the same as strings
    sym = sym.to_s
  end
  to_mappings[sym] = to
end