Macros should be declared as `aw_macro<name,arg1,arg2,...>{{macro body}}` and then
they may be used as `aw_name<arg1,arg2,...>{{}}`. It just puts `macro
body` to pattern and replaces arguments to provided ones according to
macro call. E.g.:
```
$aw_macro<test,phrase>{{phrase}}$aw_test<hello world>{{}}
```
will transform into
```
hello world
```