Implemented the `er macro for Syntax Partial.
Implemented the `er macro for Syntax Partial.

briantrice/slate-language,krfkeith/slate-language,briantrice/slate-language,krfkeith/slate-language,krfkeith/slate-language,krfkeith/slate-language,briantrice/slate-language,briantrice/slate-language,krfkeith/slate-language,krfkeith/slate-language,briantrice/slate-language,briantrice/slate-language