http://elixir-lang.org/docs/stable/elixir/URI.html#encode_query/1
# current behaviour
iex> URI.encode_query(%{"some" => ["one", "two"]})
** (ArgumentError) encode_query/1 values cannot be lists, got: ["one", "two"]
# expected behaviour
iex> URI.encode_query(%{"some" => ["one", "two"]})
"some[]=one&some[]=two"
Why lists are forbidden in this method?