this module represent a single field in a row of a positional file without a value
outputs an empty field
@type t() :: %Posexional.Field.Empty{filler: term(), size: term()}
@spec new(integer(), Keyword.t()) :: t()
@spec write(t()) :: binary()
iex> Posexional.Field.Empty.write(%Posexional.Field.Empty{filler: ?-, size: 10}) "----------" iex> Posexional.Field.Empty.write(%Posexional.Field.Empty{filler: ?\s, size: 2}) " "